Disclosed is a power steering system comprising: a control valve disposed in the steering mechanism to selectably supply a working liquid supplied from a first pump or a second pump to a pair of pressure chambers of a power cylinder providing a steering force for at least one steered wheel in accordance with a rotational steering operation of a steering wheel; a first switching valve disposed between the first pump and the control valve to switch a communication and an interruption of the working liquid between the first pump and the control valve; and a second switching valve disposed between the second pump and the control valve to switch the communication and the interruption of the working liquid between the second pump and the control valve, a communication state and an interruption state being selectably formed in the second switching valve when the first switching valve is in the communication state.