PURPOSE: To provide a two-cycle rotary internal combustion engine that has no pumping loss as in the conventional Wankel rotary engine, and higher in reliability and durability than this Wankel rotary engine.

CONSTITUTION: Both intake and exhaust ports of the conventional Wankel rotary engine are closed and these spots are set down to a second compression ignition point. In addition, a scanvenging port 4 is set up in the proper position of a side housing and an exhaust port 6 in the proper position of a rotor housing 5, respectively, and a scavenging pump 13 is set up at the outside of a cylinder. Thus, utilizing a framework of the conventional Wankel rotary engine, a two-cycle rotary engine is constituted in this way. With a two cycle-system adopted, any pumping loss in time of a four-cycle system is brought to nothing, and in consequence, heat efficiency and engine power are well improved. In addition, since the same engine power is securable with yet lower engine speed as compared with the four-cycle time, wear in seals and housings is reduced, so that durability and reliability are improved.