Provided is a valve device which can precisely adjust the flow rate while ensuring the flow rate of the fluid. A valve device includes a main actuator which receives a pressure of a supplied drive fluid and moves an operating member to an open position or closed position; an adjusting actuator arranged to receive at least a part of a force generated by the main actuator and for adjusting the position of the operating member positioned at the open position; and a pressure regulator provided in a feed path of the drive fluid to the main actuator and for regulating the pressure of the supplied drive fluid to suppress fluctuation of the pressure of the drive fluid supplied to the main actuator.