Abstract: An electric power steering apparatus comprises an input shaft transmitting a rotation from a steering wheel and an output shaft rotatably connected to the input shaft through a torsion bar relative to the input shaft. A drive motor is coaxially arranged relative to both of the input shaft and the output shaft. A reduction mechanism coaxially provided in a housing relative to the input and output shaft transmits a rotation of the drive motor to the output shaft so as to reduce the rotation of the drive motor at a constant reduction rate. A torque sensor detects a torque added to the torsion bar as a relative rotational displacement between the input shaft and the output shaft. The drive motor is rotationally controlled in accordance with the detected torque by the torque sensor.