A vehicle electro-hydraulic power steering unit includes: a steering mechanism steering a steering wheel in a steering direction; an electro-hydraulic pump; a piston mechanism assisting the steering mechanism in a steering direction; a hydraulic circuit causing an assist force to be generated in response to the steering of the steering mechanism; and a control unit controlling a motor based on an output signal from a vehicle speed sensor, a torque sensor, and a steering angle sensor. In this power steering unit, driving the motor is started when a steering torque exceeds a set torque threshold, and the torque threshold to be set is changed depending on operating conditions. Thus, a vehicle electro-hydraulic power steering unit improved in fuel consumption is obtained.