An object detection device of the present disclosure includes three reception units for receiving reflected waves resulting from reflection of a transmission wave by an object within a detection range, and a determination unit for determining presence or absence of an object to be avoided based on outputs of the three reception units. The determination unit calculates first coordinates and second coordinates at which an object is estimated to be present, based on reception times from when a transmission wave is transmitted until reflected waves are received by the three reception units, and determines whether or not the object needs to be avoided, based on a distance between the first coordinates and the second coordinates.