Inflator

The object is to provide an inflator which can be easily manufactured in a simple manufacturing process so as not to be disassembled. In an inflator, an orifice member (16) of a bottle (3) is provided with projections (43) formed on the periphery of the orifice member (16), extending in the axial direction thereof, and key grooves (47) formed in the periphery of the orifice member (16), extending in the axial direction thereof. A diffuser (7) is provided, in the inner periphery thereof, with guide grooves (49) for guiding the projections (43) of the orifice member (16) when the diffuser (7) and the orifice member (16) are coupled with each other, grooves (41) which mate with the projections (43) after the diffuser (7) or the orifice member (16) rotates, and key grooves (51) which associate with the key grooves (47) of the orifice member (16). Keys (45) which are inserted into the key grooves (47) and (51) and thereby prevent the orifice member (16) or the diffuser (7) from rotating are also provided. The orifice member (16) and the diffuser (7) are coupled with each other, either one of the components is rotated, and both components are thereby connected to each other.