PURPOSE: To secure a temperature correction factor corresponding correctly to the actual intake air temperature so as to improve control accuracy by correcting the correction factor of intake air temperature onto the higher side of intake air temperature at the time of a valve means being operated to open the communicating passage of each cylinder, compared to the non-operating time.

CONSTITUTION: In a rotary piston engine 1, plural cylinders 4 are communicated with each other by a communicating passage 16, and each opening end of the communicating passage 16 to each cylinder 4 is set as a delay-closing intake port 17 closed later than an intake port 9. The communicating passage 16 is opened in the specified operating state by a control valve 18, and the control valve 18 is controlled by a control unit 31 on the basis of detection signals from an intake temperature sensor 33 and the like. At the opened time of the control valve 18, the correction factor of intake air temperature is corrected onto the higher side of intake air temperature compared to the valve closed time. This results in obtaining a temperature correction factor corresponding correctly to the actual intake air temperature in combustion chambers 5.