An internal combustion engine (1) includes an internal combustion engine main body (20), a head cover (11, 15) attached to an upper end part of the internal combustion engine main body, and an exhaust system (34) connected to the internal combustion engine main body, and a gas-liquid separator (45, 60) for blowby gas provided in the head cover. A part of the exhaust system is positioned adjacent to the internal combustion engine main body in a first direction (X) along a cylinder row, and the gas-liquid separator is positioned in the head cover so as to be offset in the first direction.