PURPOSE: To improve starting property by opening an exhaust-port upper-edge closing value at the time of starting, in the captioned device in which said exhaust-port upper-edge closing valve for a two-cycle engine is opened in accordance with rise in engine speed.

CONSTITUTION: A closing valve EV for opening and closing the upper edge part of an exhaust port EM of a two-cycle engine Eng, is driven by a motor M. Pulses Vn from a speed signal generating circuit 1 is counted, and the valve EV is gradually opened in accordance with engine speed during the time from a defined engine speed to another defined engine speed, to obtain the optimum exhaust port opening timing corresponding to an engine speed. On the other hand, when starting an engine, the valve EV is opened by the output of a low engine speed setting circuit 4 until a set engine speed is obtained, reducing a compressed pressure to improve starting property.