The position detecting apparatus repeatedly acquires, from a radar apparatus, object information including at least an object distance as a distance between the radar apparatus and a reflecting object and a relative speed between the radar apparatus and a reflecting object. The position detecting apparatus calculates a speed ratio as a ratio between the relative speed and the travelling speed. The position detecting apparatus calculates, based on the speed ratio, a projection distance between a projected position of the reflecting object projected onto a projection plane and a position of the radar apparatus on the projection plane, the projection plane having a predetermined angle with respect to a center axis indicating a direction along which the radar waves are transmitted by the radar apparatus and including the radar apparatus. The position detection apparatus calculates the position of the reflecting object based on the calculated projection distance.