To simultaneously reduce soot and NOx by enlarging an area for low temperature combustion.

In a first combustion mode, an EGR gas amount in a combustion chamber 5 is larger than the EGR gas amount showing a peak point of soot generation and thus also no generation of soot. In second combustion mode, the EGR gas amount in the combustion chamber 5 is smaller than the value showing the peak point of the soot generation. The first and second modes are selectively performed. Water is injected from a water injection valve 37 into an intake port 8 in a high load side operation area among the operation areas performing the first combustion.