This assistance device includes: a rotating base which is provided on the floor of a room and is rotatable about an axis parallel to a vertical direction； a slide member which is provided on the rotating base and is slidable in a horizontal direction； and a support member which is provided on the slide member and supports the upper body of a person to be assisted. The slide member causes the support member to slide between a position outside the room at which the person to be assisted mounts and dismounts from the support member and a position inside the room at which the person being assisted by the support member is inside the room.
