To specify the posture of the main body of a small-sized gas container to a constant attitude by omitting flanges by using the protruding structure provided to the conventional gas apparatus for the mounting cap of the main body as an engaging section having a recessed section and making a nozzle impossible to be inserted into a connecting port by bringing the shoulder section of the protruding structure into contact with the other side when the structure is not able to be engaged with the other side.

The main body 11 of a small-sized gas container provided with a cylindrical shoulder and barrel section has a pressure-resistant bottom section 12 at one end and a mounting cap 13 provided at the other end of the main body 11 has an attaching section 17 for a valve mechanism 16 provided with a valve nozzle 14 and a siphon tube pipe 15 at one end. The cap 13 is united with the edge of the cylindrical shoulder and barrel section by means of an appropriate means at the peripheral edge section of the main body 11 at the other end. A void space 19 is formed around the attaching section 17 to accept the gas apparatus-side connection of the container. The other section 20 which can be engaged with the gas apparatus-side engaging section of the container is formed on the mounting cap 13 of the main body 11 as a recessed section. The other section 20 has such a width and depth that can accept the engaging section, side walls 24 positioned on the left and right sides of the engaging section, and an internal wall 25 which is regarded as the bottom of the recessed section. Therefore, the engaging section of the conventional gas apparatus having a protruding structure can be utilized as it is.