To obtain a pressure regulator equipped with a function for executing the fine regulation of the setting of a relief pressure in a safety valve mechanism.

In a pressure regulator having a pressure reducing function, a discharge hole 34 perforated so that a secondary chamber can be communicated with a regulating spring setting space, a valve sheet 35 arranged in the discharge hole 34, and a relief value 80 whose taper part 83 can be butted to the valve sheet 35 are mounted on a pressure receiving member 30 arranged so that pressure in the secondary chamber can be regulated into a desired set pressure by the force of the regulating spring. Also, a regulating shaft 75 is formed so as to be moved back and forth so that the top end can be butted to the relief valve 80. Thus, when the pressure in the secondary chamber reaches the set pressure by the regulating spring or more, the operating position of the relief valve 80 where the taper part of the relief part 80 and the valve sheet are separated from each other can be set by the backward and forward movement of the regulating shaft, and the fine regulation of the operating pressure (relief pressure) can be attained.