An object detection device that detects an obstacle in an object by transmitting a signal by a transmission unit, and using reflection signals by a receiving unit, the device including: a sidewall detection circuit that determines whether the vehicle is running on a road having the sidewall, based on an azimuth angle of the object, a distance from the vehicle to the object, Doppler velocities of the reflection signals, and intensities of the reflection signals; a multiple reflection position detection circuit that detects multiple reflection wave components from the reflection signals, based on the Doppler velocities, the azimuth angle, and the reflection intensities when the road is determined to have the sidewall; a detection exclusion range setting circuit that removes the detected multiple reflection wave components from the reflection signals; and an object detection circuit that detects the object using the reflection signals with the multiple reflection wave components removed.