A power steering device is provided which is capable of preventing a wrong operation from occurring in a steering control state even when an initial torque of torque detection was not detected normally due to a human error. Upon receipt of a trigger signal, a CPU reads an initial setting program from a program storage area of a ROM and executes the initial setting program in the following order of steps. That is, the CPU detects by torque detection an initial torque which is generated primarily by the cause of the difference between origin positions of a pair of resolvers 12, 12 which together with a torsion bar constitutes the torque detection. Then, the CPU operates an assist motor to rotate a steering handle from a neutral position a predetermined rotational angle in one direction about the handle axis to stop the steering handle at a first judgment position and detects a first judgment torque value by the torque detection with the steering handle being stopped at the first judgment position. Then, the CPU rotates the steering handle from the neutral position the same angular position in the other direction to stop the steering handle at a second judgment position and detects a second judgment torque value by the torque detection with the steering handle being stopped at the second judgment position. Further, the CPU judges whether the initial torque has been detected normally or not, based on the first and second judgment torque values.