A control circuit includes a computing unit, which computes a target oil pressure, a duty output unit, which outputs a drive electric current based on a result of computation of the computing unit, and a dither output unit, which applies a dither signal to a linear solenoid. The dither signal is added to the drive electric current outputted from the duty output unit and is applied to the linear solenoid. The dither output unit always applies the dither signal to the linear solenoid throughout an operation. The dither output unit reduces a pulse height of the dither signal in a dead zone in comparison to a pulse height of the dither signal in a control zone. In this way, even when an axial position of a spool is changed between the control zone and the dead zone, the amplitude of dither of the spool can be made generally constant. Thereby, it is possible to limit a change in an output oil pressure.