PURPOSE: To eliminate the delay of the changeover of valve timing in case of the sudden working of an accelerator pedal by controlling the changeover of valve timing in response to the operating speed of a throttle valve together with operation conditions regarding the engine such as the opening of the throttle valve.

CONSTITUTION: A valve timing control plate 28 is connected to the suction cam shaft 18 of an engine proper 10, an actuator 32 drives the control plate 28 through a link 30, and the valve timing of a suction valve is changed over at two stages. Signals from an engine speed sensor 40 and a throttle-valve opening sensor 38 are inputted to a control circuit 36, a function F containing throttle- valve opening degree (b) and its operating speed Δb is compared with predetermined value determined in response to the number of revolutions, and control signals are outputted to the actuator 32 by the results. Accordingly, valve timing can be changed over rapidly when the throttle valve is opened suddenly.