In an imaging system according to an embodiment of the present invention, a camera unit is configured to transmit imaging data to an information-processing unit as a downlink packet. The camera unit is configured to hold predetermined data in the imaging data as a transmission key. The information-processing unit is configured to receive the downlink packet, recognize the predetermined data in the imaging data as the transmission key, and generate a reception key on the basis of the transmission key. The information-processing unit is configured to transmit an uplink packet including the reception key and a register-setting signal indicating an imaging condition to the camera unit. The camera unit is configured to write the register-setting signal received with the reception key in a register when the transmission key and the reception key meet a predetermined condition.