In an object detection method, a moving speed v0 of a radar device and an angle θ1 defined between a moving direction of the radar device and a reception direction of a radar wave reflected on a target are acquired, a first function which expresses a relative speed v1 between the radar device and the target by the speed v0 and the angle θ1 in a non-multipath environment model and a second function which expresses the speed v1 in a multipath environment model are formed, an actual relative speed between the radar device and the target is calculated from a reception signal of the radar wave by using the multipath environment model, and it is determined that the reception signal is derived from a stationary object when a point defined by the θ1 and the actual relative speed is positioned between the first function and the second function.