An internal combustion engine includes cylinders that are divided into a first cylinder group and a second cylinder group, a cylinder reduction mechanism that holds intake valves and exhaust valves of the first cylinder group in closed states so as to establish a reduced-cylinder state. When the engine is stopped in the reduced-cylinder state, the electronic control unit provided in the engine starts the engine by ignition, by executing fuel injection and ignition in an expansion-stroke cylinder. When the first cylinder group includes an exhaust-stroke cylinder, the engine is started by ignition through fuel injection and ignition in the expansion-stroke cylinder, after a piston is moved in a reverse direction through fuel injection and ignition in the exhaust-stroke cylinder. When the first cylinder group does not include the exhaust-stroke cylinder, the engine is started by ignition, through fuel injection and ignition in the expansion-stroke cylinder and an intake-stroke cylinder.