A parking assistance device includes a range setting unit configured to set a search range searching for an obstacle based on a movement range of a host vehicle for a case in which the host vehicle is moved along a parking route, in terms of two directions, and a judgment unit configured to detect an object having a possibility of interfering with the movement of the host vehicle, based on the surrounding condition around the host vehicle, in a case in which the detected object is positioned within the search range, to judge whether the detected object is an obstacle interfering with the movement of the host vehicle along the parking route, and, in a case in which the detected object is positioned outside the search range, not to make judgment whether the detected object is the obstacle.