An ECU controls to inject a small amount of fuel in an expansion/exhaust stroke under constraint of the minimum fuel injection capability of an injector at the time of warming-up of a catalyst. The ECU controls injection of fuel in expansion/exhaust strokes (expansion/exhaust stroke injection) at the time of warming-up of a catalyst. Fuel injection control is performed so that when temperature of the catalyst becomes higher than a predetermined temperature, fuel injection in the expansion/exhaust strokes is performed for a period of a predetermined ratio in a selected cycle period. The expansion/exhaust stroke injection is not performed in the other period. By effectively utilizing oxygen absorbed on the catalyst, while suppressing slip HC, the activation time of the catalyst can be shortened.