To provide a pressure regulator simple in configuration and capable of reducing manufacturing cost and running cost and safely protecting a storage container at the time of the consumption of operation fluid.

This pressure regulator 12 for supplying inactive gas to a container 4 is provided with an entrance 14 connected to a gas source 7, an exit 16 connected through a duct 31 to the entrance and communicated with the container 4 and a first valve 36 for limiting a pressure at the exit to a prescribed maximum value Ps. The first valve is provided in a first passage 34 for connecting the duct to a flow-out orifice 27 for the discharge of the inactive gas. Also, the regulator is provided with a second valve for maintaining the pressure at the exit 16 higher than the prescribed minimum value Pi. The second valve is provided in a second passage 35 for connecting the duct to the flow-out orifice 27 for guiding liquid to the duct.