A vacuum regulating valve which is simplified in structure and where the flow rate characteristic in evacuating a vacuum vessel is improved, comprises (i) a main valve 1A of a large size which has: a principal body 4 having two main ports 11, 12 connected to a vacuum vessel 7 and a vacuum pump 8, respectively, a valve seat 14 disposed in a fluid passage connecting the ports 11, 12, a valve element 15 seated on and separated from the valve seat 14, and a shaft 20 extending from the valve element 15; and a valve element operating unit 5 for operating the valve element 15 via the shaft 20, and (ii) a sub valve 2A of a small size similar in structure to the main valve 1A. The sub valve 2A is attached to an outer side surface of a casing 10 of the main valve 1A.