A pressure regulator includes: a pressure-regulating valve configured to regulate pressure of a fluid supplied from a fluid supply source; a first pressure sensor configured to measure the pressure regulated by the pressure-regulating valve; a second pressure sensor located downstream of the first pressure sensor; a PID controller configured to produce a correction pressure command value for eliminating a difference between a pressure command value and a pressure value of the fluid measured by the second pressure sensor; and a regulator controller configured to control operation of the pressure-regulating valve so as to eliminate a difference between the correction pressure command value and a pressure value of the fluid measured by the first pressure sensor.