To make valve body mounting work to a mouthpiece efficient while avoiding structure becoming complicated in a fire extinguisher.

A valve body 13 is fitted into a mouthpiece 12 at the top of a container. An outer annular groove 47 and an inner annular groove 46 are respectively formed on the inner peripheral side of the mouthpiece 12 and on the outer peripheral side of the valve body 13. A C-type retaining ring 48 has a cutout 49 in one circumferential place and is elastically compressible in a radial direction. In mounting work of the valve body 13 to the mouthpiece 12, the C-type retaining ring 48 is elastically compressed and completely recessed into the inner annular groove 46, and then the valve body L3 is fitted into the mouthpiece 12. When the valve body 13 is fitted into the mouthpiece 12 until the inner annular groove 46 faces the outer annular groove 47, the C-type retaining ring 48 is opened by restoring force until the outer periphery abuts the bottom face of the outer annular groove 47 so as to be placed across the inner annular groove 46 and outer annular groove 47 thus fixing the mouthpiece 12 and the valve body 13 axially to each other.