A management device includes a reception strength acquirer that, when at least one reading device receives transmission signals transmitted by a plurality of transmission devices attached to respective management targets, acquires reception strengths of the transmission signals; and a degradation determinator that, on the basis of a comparison result between a newly acquired reception strength and an index value based on a plurality of reception strengths acquired during a predetermined period, determines whether or not one transmission device of the plurality of transmission devices has degraded. The one transmission device has transmitted a transmission signal corresponding to the newly acquired reception strength.