Multicylinder internal combustion engine

There is provided a multicylinder internal combustion engine. Branches (3) of an exhaust manifold (1) are connected to a common exhaust gas sensor (13) via respective exhaust communication passages (11). The exhaust gas sensor (13) detects the exhaust air-fuel ratio of each cylinder. The distance A1 from exhaust ports (10) of the engine to the exhaust gas sensor (13) is set to be shorter than the distance A2 from the exhaust ports (10) to a catalyst (9) disposed in an exhaust pipe (6).