A power steering apparatus for being protected from mud or dust, or rainwater. A sub-steering unit is provided together with a torque sensor of the power steering apparatus used in a vehicle. A steering shaft portion includes an input shaft and an output shaft, each being rotatably supported. A torque sensor portion is connected for joining the input shaft and the output shaft with the torque sensor portion sensing an amount of torque. A power assist portion is engaged with the output shaft for assisting the steering based on the amount of torque sensed by the torque sensor portion and the like. A sub-steering portion is engaged so as to connect the input shaft with the output shaft while circumventing the torque sensor portion and reducing the amount of torque. The power steering apparatus includes a column cover for covering the sub-steering portion as well as the torque sensor portion.