Parking Assistance Method and Parking Assistance Device

A parking assistance device includes: a surrounding-image generation circuit that generates a surrounding image that is a view of surroundings of a mobile object from above; an image display circuit that displays an assistance image at a position of an empty parking space in the surrounding image, the first assistance image indicating the empty parking space; and a turning determination circuit that determines whether the mobile object is turning. In a case where it is determined by the turning determination circuit that the mobile object is turning, the image display circuit prohibits the assistance image from being displayed.