To provide an optical torque and rotation sensor as well as an electric power steering device capable of securing durability and reliability even after an extended use.

A rough part 16 comprising groove parts 14 and protruding parts 15 is formed on the outside perimeter of a torsion bar 4. The light emitted from a light-emitting diode 17 is reflected on the rough part 16, and the reflected light is received with photodiodes PD1 and PD2. A control device uses a difference between voltages outputted from the PD1 and PD2 to acquire a bridge output, and detects a torque applied on the torsion bar 4 from the bridge output. The control device uses the sum of voltages outputted from the PD1 and PD2 to acquire a bridge output, and counts the protruding parts moving on the radiation light of the light-emitting diode 17 from the bridge output, for detection of a rotation speed as well.