PURPOSE: To increase a braking force, by deforming a valve driving cam for a part of cylinders in a multiple cylinder engine, and opening and closing intake and exhaust valves twice per two reciprocations of a piston during deceleration to effect a compressor action.

CONSTITUTION: Intake and exhaust valves driving cam shaft 12 for a part of cylinders in a multiple cylinder engine is formed with engine cams 19A and 20A and compressor cams 19B and 20B in juxtaposed relation with each other. The compressor cams 19B and 20B have two convex portions, and open and close the intake and exhaust valves 9 and 14 twice per two reciprocations of a piston 4 to effect a compressor action twice. As a result, it is possible to obtain a braking force twice a normal engine brake.