To prevent damage on a speed reducing part of an electric motor or a steering gear without delay in judging a collision with sidewalk boundary stones by judging the collision on the basis of change amount of steering torque and specifically control a clutch means or an electric motor at the time of the judgement.

The electric power steering device includes a judgement means M5 and a specific control means M6. The judgement means M5 judges whether the steering torque change amount is larger than a specified reference value or not. The specific control means M6 specifically controls the steering gear or the electric motor when the steering torque is judged to be larger than the specified reference value. This enable the early judgement of the collision with sidewalk boundary stones and, when steering torque change amount in danger of breakage is detected, the clutch means or the electric motor is specifically controlled without delay and the reduction part of a steering gear or the electric motor is perfectly prevented from being broken.