To obtain correct and stable pressure having a small deviation from target pressure.

A pressure passage LPc is formed between a negative pressure supplying source 2 (a first pressure supplying means) for supplying operating fluids of pressure which are different from each other and an atmosphere leading-in part 3 (a second pressure supplying means). A flow rate of the operating fluid which bypasses the pressure passage LPc is controlled by each valve opening rate of solenoid valves 4, 5, and pressure in the pressure passage is regulated.