In a turbine housing (2) of a turbocharger (1) including a turbine housing portion (7) defining a turbine chamber, an exhaust inlet passage portion 9 (9) defining an exhaust inlet passage, and a valve housing portion (12) defining a wastegate outlet passage (11) communicating with the turbine chamber via a turbine outlet passage (14) and with the exhaust inlet passage via a bypass passage (16), a wastegate valve (10) is pivotally supported by the valve housing portion to cooperate with a wastegate valve seat (34) provided at a downstream end of the bypass passage. A valve peripheral wall portion (33) of the valve housing portion includes a curved wall portion (32), and a part of the curved wall portion adjacent to the wastegate valve seat is formed with a thick wall portion (35) having a locally increased thickness.