Abstract: A pressure regulating valve comprises a bellows formed in the shape of a bottomed cylinder, a valve seat disposed opposite to a bottom portion of the bellows, a valve body provided on an outside of the bottom portion of the bellows so as to come in and out of contact with the valve seat due to expansion and contraction of the bellows, a valve body retaining meter provided on the outside of the bottom portion of the bellows and having an engaging portion used for the engagement with an outer peripheral wall portion of the bellows, the valve body retaining member serving to retain the valve body at the bottom portion of the bellows by being fixed to the outer periphery of the bottom portion of the bellows by means of the engaging portion, and a reinforcing member provided inside of the bottom portion of the bellows and located so as to be opposite to the engaging portion through a peripheral wall portion of the bellows.