When an engine driving condition has been changed from an idling condition to a vehicle running condition, a controller measures an idling period. When the idling period is longer than a determination time period immediately after the vehicle is started, a penetrating-force-decrease control is performed. Therefore, even when a piston temperature is relatively low and particulate matters are easily generated, it can be restricted that fuel adheres to the piston top-surface by performing the penetrating-force-decrease control. Further, in the penetrating-force-decrease control, since the fuel is injected at optimum injection timing, it can be avoided that emission and fuel economy are deteriorated.