PURPOSE: To properly discharge carbon and the like without increasing an inner EGR quantity by providing a slit-shaped peri-exhaust port which opens to a trocoidal surface of a rotary housing, and setting a hole opening timing substantially synchronous with a hole closing timing of a side exhaust port.

CONSTITUTION: In a two-rotor type rotary engine 10, a casing 13 formed of a rotor housing 11 and a pair of side housings 12 arranged at both the sides in provided. An intake port 18 and an side exhaust port 25 are opened to the part which forms intake and exhaust stroke actuation chambers 17a, 17c in the side housing 12. A peri-exhaust port 27 is opened to the part which forms the exhaust stroke actuation chamber 17c of the trocoidal surface of the rotor housing 11. The peri-exhaust port 27 is formed as a slit-shaped port which has a narow width in the circumferential direction of the trocoidal surface of the rotor housing 11. A hole opening timing is set substantially synchronous with a hole closing timing of the side exhaust port 25.