To take out energy same level as or higher level than energy which former internal combustion engines can generate, without causing a problem attributable to fuel resource.

This engine comprises a housing 101 provided with an intake port 107 and an exhaust port 109, an inner chamber 103 in the housing, and a rotor 105 provided in the inner chamber 103. The rotor 105 includes operation surfaces "a", "b", "c", "d", "e" and can form operation chambers A, B, C, D, E sealed by the operation surfaces and an inner circumference surface of the housing 101. The housing 101 is provided with an auxiliary chamber 106 made to communicate with the inner chamber 103 by a first through-hole 108a and a second through-hole 108b. The first through-hole can temporarily communicate with the intake port. The second through-hole can temporarily communicate with the exhaust port. The intake port and the exhaust port cannot communicate via the first through-hole and the second through-hole. Two operation chambers made to communicate with the auxiliary chamber via the first through-hole and the second through-hole can be temporarily sealed.