PURPOSE: To provide a switching motor for a pressure regulating valve which supplies controlled pressure to the vacuum chamber of a diaphragm EGR valve to make installation easier as well as to enable advanced control.

CONSTITUTION: An EGR valve 1 which is provided in an EGR passage 5 which allows the intake system 3 and exhaust system 4 of an engine 2 to be in communication is organized such that the inside of a diaphragm case is partitioned by a diaphragm 12 into a vacuum chamber 13 and an atmospheric pressure chamber 14 and a valve disc 16 coupled via a rod 15 to the center of a diaphragm 12 is separated from a valve seat 18 in the EGR passage 5. The EGR passage 5 is opened and closed by introducing controlled pressure regulated by the pressure regulating valve 20 into the vacuum chamber 13. In addition, the pressure regulating valve 20 partitions the inside of the diaphragm case 21 into the vacuum chamber 23 and the atmospheric pressure chamber 24 and a stepping motor 44 provided in the upper diaphragm case 21 is used to separate a valve disc 42 from a valve seat 42 via a nut member and an elevating rod 43.