Abstract: A housing (16) comprises a first housing (17) and a second housing (18). The first housing (17) is fixed to a gas cylinder (1) and is provided with a cylinder main valve (3) which is manually opened and closed. The second housing (18) is provided with a main stop valve (4) of an electromagnetically opening and closing valve. The second housing (18) is removably fixed to the first housing (17) by a tightening bolt (39). In this state where the second housing (18) is fixed to the first housing (17), the cylinder main valve (3) has a first valve chamber (44) communicated with a second valve chamber (63) of the main stop valve (4).