TURBINE HOUSING AND TURBOCHARGER

A turbine housing (31) for an internal combustion engine (1), the turbine housing includes a coolant passage (39) and exhaust gas flow path (34, 36). The exhaust gas flow path (34, 36) is configured to pass exhaust gas of the internal combustion engine, a turbine wheel (33) is arranged in the exhaust gas flow path, the exhaust gas flow path include a first portion (40), the first portion is disposed further on the exhaust gas downstream side than the turbine wheel (33) in the exhaust gas flow path (34, 36), and the inner diameter of the first portion gradually increases toward the exhaust gas downstream side.