diff --git a/compiler/erg_compiler/codegen.rs b/compiler/erg_compiler/codegen.rs
index 98e0b3f6..952c343e 100644
--- a/compiler/erg_compiler/codegen.rs
+++ b/compiler/erg_compiler/codegen.rs
@@ -1859,8 +1859,8 @@ impl PyCodeGenerator {
             }
             // _: (Int, Str)
             TypeSpec::Tuple(tup) => {
-                let len = tup.len();
-                for (i, t_spec) in tup.into_iter().enumerate() {
+                let len = tup.tys.len();
+                for (i, t_spec) in tup.tys.into_iter().enumerate() {
                     if i != 0 && i != len - 1 {
                         self.dup_top();
                     }
diff --git a/compiler/erg_compiler/context/instantiate.rs b/compiler/erg_compiler/context/instantiate.rs
index c7326fb2..2889e914 100644
--- a/compiler/erg_compiler/context/instantiate.rs
+++ b/compiler/erg_compiler/context/instantiate.rs
@@ -699,9 +699,9 @@ impl Context {
                 }
                 Ok(set_t(elem_t, len))
             }
-            TypeSpec::Tuple(tys) => {
+            TypeSpec::Tuple(tup) => {
                 let mut inst_tys = vec![];
-                for spec in tys {
+                for spec in tup.tys.iter() {
                     inst_tys.push(self.instantiate_typespec(
                         spec,
                         opt_decl_t,
diff --git a/compiler/erg_compiler/context/register.rs b/compiler/erg_compiler/context/register.rs
index ee21ec04..51b5e888 100644
--- a/compiler/erg_compiler/context/register.rs
+++ b/compiler/erg_compiler/context/register.rs
@@ -188,7 +188,11 @@ impl Context {
             self.locals.insert(ident.name.clone(), vi);
             return Ok(());
         }
-        self.validate_var_sig_t(ident, sig.t_spec.as_ref(), body_t, Normal)?;
+        let (var_t, errs) =
+            match self.validate_var_sig_t(ident, sig.t_spec.as_ref(), body_t, Normal) {
+                Ok(()) => (body_t.clone(), None),
+                Err(errs) => (Type::Failure, Some(errs)),
+            };
         let muty = Mutability::from(&ident.inspect()[..]);
         let py_name = if let Some(vi) = self
             .decls
@@ -201,7 +205,7 @@ impl Context {
         };
         let vis = ident.vis();
         let vi = VarInfo::new(
-            body_t.clone(),
+            var_t,
             muty,
             vis,
             VarKind::Defined(id),
@@ -211,7 +215,11 @@ impl Context {
         );
         log!(info "Registered {}::{}: {}", self.name, ident.name, vi);
         self.locals.insert(ident.name.clone(), vi);
-        Ok(())
+        if let Some(errs) = errs {
+            Err(errs)
+        } else {
+            Ok(())
+        }
     }
 
     /// 宣言が既にある場合、opt_decl_tに宣言の型を渡す
diff --git a/compiler/erg_compiler/hir.rs b/compiler/erg_compiler/hir.rs
index 45700145..a2dad602 100644
--- a/compiler/erg_compiler/hir.rs
+++ b/compiler/erg_compiler/hir.rs
@@ -159,16 +159,7 @@ impl NestedDisplay for Args {
     }
 }
 
-impl From<Vec<Expr>> for Args {
-    fn from(exprs: Vec<Expr>) -> Self {
-        Self {
-            pos_args: exprs.into_iter().map(PosArg::new).collect(),
-            var_args: None,
-            kw_args: Vec::new(),
-            paren: None,
-        }
-    }
-}
+// do not implement From<Vec<Expr>> to Args, because it will miss paren info (use `values`)
 
 impl_display_from_nested!(Args);
 
@@ -183,6 +174,8 @@ impl Locational for Args {
                 self.pos_args.first().unwrap(),
                 self.pos_args.last().unwrap(),
             )
+        } else if let Some(va) = self.var_args.as_ref() {
+            va.loc()
         } else {
             Location::Unknown
         }
@@ -206,6 +199,15 @@ impl Args {
         }
     }
 
+    pub fn values(exprs: Vec<Expr>, paren: Option<(Token, Token)>) -> Self {
+        Self::new(
+            exprs.into_iter().map(PosArg::new).collect(),
+            None,
+            vec![],
+            paren,
+        )
+    }
+
     pub fn empty() -> Self {
         Self::new(vec![], None, vec![], None)
     }
diff --git a/compiler/erg_compiler/lower.rs b/compiler/erg_compiler/lower.rs
index c1338433..07f95369 100644
--- a/compiler/erg_compiler/lower.rs
+++ b/compiler/erg_compiler/lower.rs
@@ -364,7 +364,7 @@ impl ASTLowerer {
             array.l_sqbr,
             array.r_sqbr,
             elem_t,
-            hir::Args::from(new_array),
+            hir::Args::values(new_array, None),
         ))
     }
 
@@ -428,12 +428,12 @@ impl ASTLowerer {
     fn lower_normal_tuple(&mut self, tuple: ast::NormalTuple) -> LowerResult<hir::NormalTuple> {
         log!(info "entered {}({tuple})", fn_name!());
         let mut new_tuple = vec![];
-        let (elems, _) = tuple.elems.into_iters();
+        let (elems, .., paren) = tuple.elems.deconstruct();
         for elem in elems {
             let elem = self.lower_expr(elem.expr)?;
             new_tuple.push(elem);
         }
-        Ok(hir::NormalTuple::new(hir::Args::from(new_tuple)))
+        Ok(hir::NormalTuple::new(hir::Args::values(new_tuple, paren)))
     }
 
     fn lower_record(&mut self, record: ast::Record) -> LowerResult<hir::Record> {
@@ -526,7 +526,7 @@ impl ASTLowerer {
         }
         Ok(normal_set)
         */
-        let elems = hir::Args::from(new_set);
+        let elems = hir::Args::values(new_set, None);
         // check if elem_t is Eq
         if let Err(errs) = self.ctx.sub_unify(&elem_t, &mono("Eq"), elems.loc(), None) {
             self.errs.extend(errs);
diff --git a/compiler/erg_parser/ast.rs b/compiler/erg_parser/ast.rs
index 5eb72307..a34225d7 100644
--- a/compiler/erg_parser/ast.rs
+++ b/compiler/erg_parser/ast.rs
@@ -1916,6 +1916,34 @@ impl SetWithLenTypeSpec {
     }
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct TupleTypeSpec {
+    pub parens: Option<(Token, Token)>,
+    pub tys: Vec<TypeSpec>,
+}
+
+impl fmt::Display for TupleTypeSpec {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "({})", fmt_vec(&self.tys))
+    }
+}
+
+impl Locational for TupleTypeSpec {
+    fn loc(&self) -> Location {
+        if let Some((lparen, rparen)) = &self.parens {
+            Location::concat(lparen, rparen)
+        } else {
+            Location::concat(self.tys.first().unwrap(), self.tys.last().unwrap())
+        }
+    }
+}
+
+impl TupleTypeSpec {
+    pub fn new(parens: Option<(Token, Token)>, tys: Vec<TypeSpec>) -> Self {
+        Self { parens, tys }
+    }
+}
+
 /// * Array: `[Int; 3]`, `[Int, Ratio, Complex]`, etc.
 /// * Dict: `[Str: Str]`, etc.
 /// * And (Intersection type): Add and Sub and Mul (== Num), etc.
@@ -1933,7 +1961,7 @@ pub enum TypeSpec {
     /* Composite types */
     Array(ArrayTypeSpec),
     SetWithLen(SetWithLenTypeSpec),
-    Tuple(Vec<TypeSpec>),
+    Tuple(TupleTypeSpec),
     Dict(Vec<(TypeSpec, TypeSpec)>),
     Record(Vec<(Identifier, TypeSpec)>),
     // Option(),
@@ -1964,7 +1992,7 @@ impl fmt::Display for TypeSpec {
             Self::Or(lhs, rhs) => write!(f, "{lhs} or {rhs}"),
             Self::Array(arr) => write!(f, "{arr}"),
             Self::SetWithLen(set) => write!(f, "{set}"),
-            Self::Tuple(tys) => write!(f, "({})", fmt_vec(tys)),
+            Self::Tuple(tup) => write!(f, "{tup}"),
             Self::Dict(dict) => {
                 write!(f, "{{")?;
                 for (k, v) in dict.iter() {
@@ -2003,8 +2031,7 @@ impl Locational for TypeSpec {
             }
             Self::Array(arr) => arr.loc(),
             Self::SetWithLen(set) => set.loc(),
-            // TODO: ユニット
-            Self::Tuple(tys) => Location::concat(tys.first().unwrap(), tys.last().unwrap()),
+            Self::Tuple(tup) => tup.loc(),
             Self::Dict(dict) => Location::concat(&dict.first().unwrap().0, &dict.last().unwrap().1),
             Self::Record(rec) => Location::concat(&rec.first().unwrap().0, &rec.last().unwrap().1),
             Self::Enum(set) => set.loc(),
diff --git a/compiler/erg_parser/desugar.rs b/compiler/erg_parser/desugar.rs
index 08bbe4f2..58fb4d5f 100644
--- a/compiler/erg_parser/desugar.rs
+++ b/compiler/erg_parser/desugar.rs
@@ -17,9 +17,9 @@ use crate::ast::{
     Identifier, KeyValue, KwArg, Lambda, LambdaSignature, Literal, Methods, MixedRecord, Module,
     NonDefaultParamSignature, NormalArray, NormalDict, NormalRecord, NormalSet, NormalTuple,
     ParamPattern, ParamRecordAttr, Params, PatchDef, PosArg, Record, RecordAttrOrIdent,
-    RecordAttrs, Set as astSet, SetWithLength, Signature, SubrSignature, Tuple, TypeAppArgs,
-    TypeBoundSpecs, TypeSpec, TypeSpecWithOp, UnaryOp, VarName, VarPattern, VarRecordAttr,
-    VarSignature,
+    RecordAttrs, Set as astSet, SetWithLength, Signature, SubrSignature, Tuple, TupleTypeSpec,
+    TypeAppArgs, TypeBoundSpecs, TypeSpec, TypeSpecWithOp, UnaryOp, VarName, VarPattern,
+    VarRecordAttr, VarSignature,
 };
 use crate::token::{Token, TokenKind, COLON, DOT};
 
@@ -766,7 +766,8 @@ impl Desugarer {
                     );
                 }
                 if param.t_spec.is_none() {
-                    param.t_spec = Some(TypeSpecWithOp::new(COLON, TypeSpec::Tuple(tys)));
+                    let t_spec = TypeSpec::Tuple(TupleTypeSpec::new(tup.elems.parens.clone(), tys));
+                    param.t_spec = Some(TypeSpecWithOp::new(COLON, t_spec));
                 }
                 param.pat = buf_param;
             }
@@ -901,7 +902,8 @@ impl Desugarer {
                     );
                 }
                 if sig.t_spec.is_none() {
-                    sig.t_spec = Some(TypeSpecWithOp::new(COLON, TypeSpec::Tuple(tys)));
+                    let t_spec = TypeSpec::Tuple(TupleTypeSpec::new(tup.elems.parens.clone(), tys));
+                    sig.t_spec = Some(TypeSpecWithOp::new(COLON, t_spec));
                 }
                 sig.pat = buf_sig;
                 insertion_idx
diff --git a/compiler/erg_parser/parse.rs b/compiler/erg_parser/parse.rs
index bf98dd60..474870a6 100644
--- a/compiler/erg_parser/parse.rs
+++ b/compiler/erg_parser/parse.rs
@@ -1150,7 +1150,7 @@ impl Parser {
                         enum_unwrap!(stack.pop(), Some:(ExprOrOp::Expr:(_))),
                     ));
                     let tup = self
-                        .try_reduce_tuple(first_elem, false)
+                        .try_reduce_nonempty_tuple(first_elem, false)
                         .map_err(|_| self.stack_dec())?;
                     stack.push(ExprOrOp::Expr(Expr::Tuple(tup)));
                 }
@@ -1329,7 +1329,7 @@ impl Parser {
                         enum_unwrap!(stack.pop(), Some:(ExprOrOp::Expr:(_))),
                     ));
                     let tup = self
-                        .try_reduce_tuple(first_elem, line_break)
+                        .try_reduce_nonempty_tuple(first_elem, line_break)
                         .map_err(|_| self.stack_dec())?;
                     stack.push(ExprOrOp::Expr(Expr::Tuple(tup)));
                 }
@@ -1423,7 +1423,7 @@ impl Parser {
             .map_err(|_| self.stack_dec())?;
         let first_elem = PosOrKwArg::Kw(KwArg::new(keyword, t_spec, rhs));
         let tuple = self
-            .try_reduce_tuple(first_elem, false)
+            .try_reduce_nonempty_tuple(first_elem, false)
             .map_err(|_| self.stack_dec())?;
         self.level -= 1;
         Ok(tuple)
@@ -2097,7 +2097,11 @@ impl Parser {
         Err(())
     }
 
-    fn try_reduce_tuple(&mut self, first_elem: PosOrKwArg, line_break: bool) -> ParseResult<Tuple> {
+    fn try_reduce_nonempty_tuple(
+        &mut self,
+        first_elem: PosOrKwArg,
+        line_break: bool,
+    ) -> ParseResult<Tuple> {
         debug_call_info!(self);
         let mut args = match first_elem {
             PosOrKwArg::Pos(pos) => Args::new(vec![pos], vec![], None),
@@ -3284,16 +3288,16 @@ impl Parser {
         }
     }
 
-    fn tuple_to_tuple_type_spec(tuple: Tuple) -> Result<Vec<TypeSpec>, ParseError> {
+    fn tuple_to_tuple_type_spec(tuple: Tuple) -> Result<TupleTypeSpec, ParseError> {
         match tuple {
             Tuple::Normal(tup) => {
                 let mut tup_spec = vec![];
-                let (elems, ..) = tup.elems.deconstruct();
+                let (elems, .., parens) = tup.elems.deconstruct();
                 for elem in elems.into_iter() {
                     let value = Self::expr_to_type_spec(elem.expr)?;
                     tup_spec.push(value);
                 }
-                Ok(tup_spec)
+                Ok(TupleTypeSpec::new(parens, tup_spec))
             }
         }
     }