A communication device includes a communication unit that receives a reception window size from a reception side communication device and transmits a packet of a transmission amount corresponding to a transmission window size to the reception side communication device; and a control unit that determines whether a channel with respect to the reception side communication device is in a broad band and high delay circumstance, changes a first state where the transmission window size is a first window size which is not larger than the reception window size to a second state wherein the transmission window size is a second window size which is larger than the reception window size when the channel is determined as the broad band and high delay circumstance, and transmits the packet of the transmission amount larger than the reception window size in the second state.