A relay device according to the present invention includes: a receiving unit which receives a frame; a transmitting unit which transmits a frame; a frame determination unit which stores therein the first frame when the frame determination unit determines that the received frame is the first frame; a proxy ACK generation unit which generates a third frame which is a proxy frame of a second frame which is a frame to be transmitted from the receiving device, as a receipt acknowledgement to the first frame; and a communication control unit which: causes the transmitting unit to transmit the third frame; sets an extended active period in the inactive period subsequent to the active period; and transmits the first frame in the extended active period when the receiving unit does not receive the second frame within a predetermined period after reception of the first frame.