An object detection device is applied to an object detection system which includes an object detection sensor installed in a vehicle so as to be oriented outward to detect an object around the vehicle. The object detection device includes: an error-handling control section that notifies a user of a detection error, if any, occurring in the object detection sensor, and brings the object detection system into an error-handling state; an action determination section that determines whether an error correction action has been performed by a user to correct the detection error, under conditions where the user has been notified of the detection error occurring in the object detection sensor; and a cancellation control section that relaxes predetermined cancellation conditions for cancelling the error-handling state when the error correction action is determined to have been performed, compared to when not performed.