In the case of performing a main injection, and a sub-injection that injects a minute amount of fuel in a region (i) in Fig. 3, a check is conducted to determine whether or not the minute amount of fuel is injected accurately. In a specific cycle at a time of cold starting when catalyst warm-up control is performed, the main injection is omitted and a checking injection corresponding to a sub-injection is performed. Injection conditions of the in-cylinder injection valve 28 are made uniform between the checking injection and the sub-injection. A fuel amount that is actually injected from the in-cylinder injection valve 28 in the specific cycle is calculated based on the air-fuel ratio of exhaust gas discharged from the engine 10 and an in-cylinder air amount, and is compared with a fuel amount that theoretically should be injected from the in-cylinder injection valve 28.