A disclosed medical device includes a first data transmission path that includes a first insulation device connecting a secondary circuit and a patient circuit such that serial data output from the secondary circuit is transmitted to the patient circuit while maintaining electrical insulation between the secondary circuit and the patient circuit; a second data transmission path that includes a second insulation device connecting the secondary circuit and the patient circuit such that the serial data transmitted from the secondary circuit to the patient circuit via the first data transmission path is fed back to the secondary circuit while maintaining electrical insulation between the secondary circuit and the patient circuit; and a comparison determination unit that is provided in the secondary circuit and compares the serial data output from the secondary circuit with the serial data fed back to the secondary circuit.