Power steering system

A power steering system, comprising:

• a steering valve (9) for controlling a power cylinder (8);
• a variable orifice (a) provided upstream from the steering valve (9);
• a solenoid (SOL) for controlling a degree of opening of the variable orifice (a);
• a controller (C) for controlling a solenoid current instruction value (SI) used for driving the solenoid (SOL);
• a steering angle sensor (14) and a vehicle speed sensor (15) which are connected to the controller (C);
• and
• a flow control valve (V) for dividing a flow, supplied from a pump (P), into a control flow (QP) supplied to the steering valve (V) in accordance with the degree of opening of the variable orifice (a), and a return flow (QT) circulating back to a tank (T) or the pump (P),
• the controller (C) determining the solenoid current instruction value (SI) on the basis of a current instruction value (I1) in accordance with a steering angle supplied from the steering angle sensor, a current instruction value (I2) in accordance with a steering angular velocity, and current instruction values (I3, I4) in accordance with a vehicle speed, and comprising a delay control section for lessening the rate of decrease only when an incoming current instruction value is abruptly decreased, and outputting the resulting current instruction value.