A valve member includes a first communication passage for allowing a first passage to communicate with a first pressure chamber. When a pressure-receiving member contacts the valve member, a communication between the first communication passage and the first pressure chamber is shut. Magnetic force of a permanent magnet urges a shaft toward the pressure-receiving member. While a coil is not energized, when pressure inside a second passage rises, the pressure-receiving member leaves the valve member due to pressure difference between pressure inside the first pressure chamber and pressure inside a second pressure chamber, so that the first passage communicates with the second passage through the first communication passage. When the coil is energized, magnetic repelling force is introduced between a stator core and the permanent magnet, so that the pressure-receiving member and the shaft depart from the valve member to allow the first passage to communicate with the second passage.