PURPOSE: To improve the transient response characteristic, by providing a pressure regulator valve unit, which is urged so as to normally cut off a communication condition between a control pressure oil port communicating with a movable pulley pressure oil chamber and a drain port, in a pressure regulating valve.

CONSTITUTION: A large contour hole 22a, which is provided in a case main unit 22 of a pressure regulating valve 20, provides a pressure regulator valve unit 40 which is urged so as to normally cut off a communication condition between a control pressure oil port 37, communicating with a movable pulley pressure oil chamber 21 of a driven pulley unit 9, and a drain port 43. In this way, a passage part, for releasing pressure oil from the control pressure oil port 37 to the drain port 43, large increases a sectional area, and a belt type continuously variable transmission, which can promptly release a large amount of pressure oil when a pressure of working oil in the movable pulley pressure oil chamber 21 increases, enables the transient response characteristic to be improved.