<p>A power steering device capable of being smoothly and simply assembled and having high reliability. A power steering device includes torque detection means having a torsion bar (7) fixed at one end to a steering shaft (2) and at the other end to an output shaft (6) on the electric motor (M) side, a coil assembly (12) fitted on the torsion bar (7) and whose magnetism changes with torsion of the torsion bar (7), and a sensor circuit board (19) for detecting a change in the magnetism of the coil assembly (12). To construct the torque detection means, the coil assembly (12) and the sensor circuit board (19) are assembled to a base plate (17) to form a sensor assembly (11), and this enables the coil assembly (12) and the sensor circuit board (19) to be assembled at a time.</p>
