mounting cup 10 and the notch 11 referring to fig1 since the excess pressure gas outlet 13 is positioned in this manner and the valve stem housing 20 and the safety valve housing 31 are integrally formed lt referring to fig1 c gt it is possible to form a number of cavities in a mold in the same size upon the injection molding and therefore it is possible to remarkably reduce the manufacturing cost the portable gas container charged with the butane gas discharges the gas through a valve stem which is installed through the center of the mounting cup 10 connected to the top of the container when the pressure in the container becomes higher than predetermined pressure the excess pressure gas within the container is instantaneously and sufficiently released to the outside through the safety valve 30 of the present invention so that the pressure inside the container sufficiently lowers the safety valve 30 basically comprises the safety valve housing 31 the shaft 32 positioned in the safety valve housing 31 the stopper 34 fitted around a top end of the shaft 32 the spring 33 fitted around a body of the shaft 32 and first and second gaskets 35 36 to prevent the leak.