To provide a heating power adjusting device and a gas heating cooker capable of reliably obtaining a click feeling when they are operated at predetermined heating power even if a heating power adjusting lever is operated in any direction.

A needle valve is inserted in a valve sliding part which is vertically provided in a gas passage to communicate with a burner. A needle pin 52 of the needle valve is inserted in a cam groove 81. The needle pin 52 is pressed against a sliding face 82 being the lower face of the cam groove 81 at all times by the self weight of the needle valve and a compression spring. The needle pin 52 slides on the sliding face 82 according to the turning operation of a heating power adjusting lever. A stepped part 85 is provided at the sliding face 82. The position of the stepped part 85 is a rice cooking heating power position. Thus, when the needle pin 52 reaches the rice cooking heating power position, the click feeling can be reliably felt by a user through the heating power adjusting lever.