A cock apparatus of automatic ignition type for use in a gas appliance including an ignition handle, a valve member disposed within the cock body for rotation with the turning movement of the ignition handle thereby supplying gas to a main burner and a pilot burner, and a spark generator generating sparks for igniting the pilot burner in response to the turning movement of the ignition handle. The cock comprises a rotary shaft capable of free rotation and restrained rotation relative to the valve member and normally urged by a spring to rotate in the closing direction of the valve member, and a heat sensor for sensing ignition and non-ignition of the main burner, the heat sensor being operatively connected to the rotary shaft so that the rotary shaft and the valve member can be automatically rotated in the valve closing direction by the force of the spring in the event of ignition failure of gas or accidental extinction of gas flame burning on the main burner.