PARKING ASSISTANCE DEVICE

In a method of detecting a parkable space using only a sonar installed on a side of a vehicle, automatic parking assistance cannot be implemented at an early stage, and an environment in which automatic parking assistance is possible is limited. In a parking assistance device including a parkable space setting unit that sets a parkable space existing ahead of the vehicle based on information from a front detector, the parkable space setting unit corrects the parkable space based on information on the parkable space acquired by a side detector when the vehicle passes by the parkable space.