A pressure regulator configured to regulate a working fluid by a pilot pressure, including: a spool valve mechanism having a spool; a biasing mechanism having a pilot-pressure chamber and a pilot piston, the biasing mechanism being configured to bias the spool toward the other end of the pressure regulator in its axial direction by a pressure of the working fluid in the pilot-pressure chamber; a counter biasing mechanism having a regulated-pressure chamber and a counter biasing piston, the counter biasing mechanism being configured to bias the spool toward one end of the pressure regulator in the axial direction by a pressure of the working fluid in the regulated-pressure chamber; and at least one of a first damping mechanism configured to damp a movement of the pilot piston and a second damping mechanism configured to damp a movement of the counter biasing piston.