An electric power steering device includes a steering shaft that is coupled to the steering wheel, an output shaft that is coupled to the steering shaft via a torsion bar, a torque sensor that detects a steering torque that acts on the torsion bar, a sensor case to which a magnetic material, which is a component of the torque sensor, is fixed, an upper column tube that rotatably supports the steering shaft, and a lower column tube that is movable relative to the upper column tube, wherein the lower column tube and the sensor case are configured as an integrated part made of a resin material.