PURPOSE: To provide a supercharger engine of which torque and fuel consumption can be remarkably improved.

CONSTITUTION: An intake rotary valve 8 and an exhaust rotary valve 9 which are are formed into cylindrical shapes, provided with hollow parts, and have a little larger diameters than intake and exhaust ports 6, 7, are respectively fitted to the intake and exhaust ports 6, 7 positioned on the same height, the circumferential walls of the intake rotary valve 8 and the exhaust rotary valve 9 of the corresponding parts to the intake and exhaust ports 6, 7 are opened, and the positions of the valves at least opposite side of the opening and shifted in the axial direction are opened. The intake and exhaust rotary valves 8, 9 are positiond so that at the scavenging process, the intake and exhaust rotary valves 8, 9 are both opened, and at the intake process, the exhaust rotary valve 9 is closed and the intake rotary valve is opened, and further the intake rotary valve 8 and the exhaust rotary valve 9 and a crankshaft 14 are interlocked with each other.