A supply switching valve (140) can selectively switch the communication between a supply path (104) and a retard supply path (110) and the communication between the supply path (104) and an advance supply path (120). Check valves (111, 121) are arranged in the retard supply path (110) and the advance supply path (120), respectively. The check valves (111, 121) allow the working oil to be supplied from an oil pump (102) to each oil pressure chamber and prohibit the reverse flow of the working oil from each oil pressure chamber to the oil pump (102). A discharge switching valve (150) is configured independently of the supply switching valve (140) and can selectively switch the communication between a retard discharge path (130) and a discharge path (134) and the communication between an advance discharge path (132) and the discharge path (134).