PARKING ASSISTANCE DEVICE

A parking assistance device () is provided with distance sensors (FL, FR, RL, RR) which transmit detection waves laterally with respect to a host vehicle () while the host vehicle () travels and receive reflected waves of the detection waves, a reflection point calculating unit () which calculates a reflection point indicating a position where the detection wave is reflected, a grouping unit () which groups the reflection points, a parking space pitch calculating unit () which calculates a parking space pitch indicating a width of each parking space by using periodicity of a shape of a reflection point group set by grouping, a parking target area setting unit () which sets a parking target area which is a target of perpendicular parking by the host vehicle (), and a parking assistance controlling unit () which guides the host vehicle () to the parking target area on the basis of the parking space pitch.