PURPOSE: To prevent the closing of an opening and closing valve due to the delay of operation of a combustion detecting means, etc. by limiting the speed of closing of the valve to value lower than predetermined speed when closing the opening and closing valve energized in the direction of closing by the force of a spring.

CONSTITUTION: When closing the opening and closing valve 4 energized in the direction of closing by the force of the spring 6, an intermittent rotary mechanism 11 consisting of an escape wheel 12, which limits the speed of closing to value lower than the predetermined speed and is fitted to a valve shaft 4c, and an ankle 13, which is connected to the escape wheel 12 and intermittently turns the wheel, is mounted. When detaching the operation knob 4b of the opening and closing valve 4, the opening and closing valve 4 is not closed completely even when the operation of a combustion detector 10, etc. is delayed because a cam 8 is slowly rotated and returned in the direction of energizing of the spring 6 by the operation of the intermittent rotary mechanism 11. Accordingly, trouble such as the closing of an automatic valve is not generated due to said delay of operation though a gas burner 2 is ignited positively.