A ghost removal method includes steps of detecting, estimating and excluding. In the detecting, a position and a relative speed of a target moving object, and a position of a surrounding stationary object are detected with radio waves. In the estimating, a position and a relative speed of a ghost by the target moving object are estimated based on the detected position and relative speed of the target moving object and the position of the surrounding stationary object. In the excluding, a detected point where the estimated position and the relative speed of the ghost are detected is excluded from a candidate detection point of a moving object which is detected with radio waves.