A device for detecting an object, comprising: a receiver configured to receive information about the object detected by a sensor (11, 12); a plurality of detection circuits (113, 123, 133) configured to detect the object from the received information by performing detection processes for the object at different distance ranges, wherein the detection processes have higher priorities for shorter distance ranges; and a control circuit configured to control the detection circuits, wherein the control circuit is configured to detect whether the detection circuits are in an abnormal state, on the basis of a change in a state of the detection circuits, wherein, when the control circuit detects that a first detection circuit of the plurality of detection circuits is in an abnormal state, the control circuit is configured to - cause the first detection circuit to stop a detection process being performed by the first detection circuit; and - cause, on the basis of priorities assigned to the detection processes for respective objects, one of the plurality of detection circuits, being a detection circuit configured to perform a detection process corresponding to the lowest priority, to detect the object by causing the one of the plurality of detection circuits to stop performing its respective detection process, and to perform the detection process that was performed by the first detection circuit. a receiver configured to receive information about the object detected by a sensor (11, 12); a plurality of detection circuits (113, 123, 133) configured to detect the object from the received information by performing detection processes for the object at different distance ranges, wherein the detection processes have higher priorities for shorter distance ranges; and a control circuit configured to control the detection circuits, wherein the control circuit is configured to detect whether the detection circuits are in an abnormal state, on the basis of a change in a state of the detection circuits, wherein, when the control circuit detects that a first detection circuit of the plurality of detection circuits is in an abnormal state, the control circuit is configured to - cause the first detection circuit to stop a detection process being performed by the first detection circuit; and - cause, on the basis of priorities assigned to the detection processes for respective objects, one of the plurality of detection circuits, being a detection circuit configured to perform a detection process corresponding to the lowest priority, to detect the object by causing the one of the plurality of detection circuits to stop performing its respective detection process, and to perform the detection process that was performed by the first detection circuit. - cause the first detection circuit to stop a detection process being performed by the first detection circuit; and - cause, on the basis of priorities assigned to the detection processes for respective objects, one of the plurality of detection circuits, being a detection circuit configured to perform a detection process corresponding to the lowest priority, to detect the object by causing the one of the plurality of detection circuits to stop performing its respective detection process, and to perform the detection process that was performed by the first detection circuit.