Abstract: Disclosed is a rotary combustion unit for a rotary internal combustion engine usually cooperated with a cooperative compressor unit having a two-blade cam piston with a main shaft rotated in a cylinder, two spring-loaded reciprocating gate members reciprocated by the cam piston formed a power stroke and a reset stroke being alternatively repeated while the spark plugs ignite the compressed mixed gas delivered by the cooperative compressor unit repeatedly for a certain instant; and a series of sealing devices disposed to all moving contact surfaces to seal the leakages in all condition even if the contact surfaces were worn out due to a long period of engine running.