To recirculate oil between a pair of actuators swinging a lifter plate in a lifter mechanism provided with the swingable lifter plate.

This internal combustion engine is provided with a lifter body 158 having upper and lower faces, the lifter plate 116 swinging around a shaft above the lifter body 158, a fluid chamber 156 in the lifter body 158 provided in end parts on both sides across a shaft of the lifter plate 116, a piston 152 in the fluid chamber 156, a pair of hydraulic actuators 105, 106 provided with a spring 154 energizing the piston 152 on a side where they come into contact with the lifter plate 116, lines 110, 111, 112, 113 for supplying working fluid into the fluid chamber 156 of the hydraulic actuators 105, 106, and a control valve 109 for controlling flow of working fluid to the hydraulic actuator on one side from the hydraulic actuator on the other side.