To provide a pressure release valve in which a valve element is prevented from being dropped out of a valve body in pressure release.

In a valve element 17 integrated into an assembly hole 13 of a valve body 11, a large diameter part 17a and a shaft part 17c, the diameter of which is smaller than that of the large diameter part 17a, are formed integrally and the shaft part 17c is supported in a through-hole 18 in a slidable manner. In a boundary part between the large diameter part 17a and the shaft part 17c, a step part 17d is formed and inside of the assembly hole 13, a stopper 16b is provided on a moving locus of the step part 17d in an axial direction when the valve element 17 is opened.