A communication apparatus includes the first memory unit which stores data to be a sending target to another communication apparatus and the second memory unit accessible at higher speed than the first memory unit, and transfers the sending target data to the second memory unit concurrently with transfer of the data to the first memory unit. The communication apparatus sends the sending target data from the second memory unit to the other communication apparatus and discards the data from the second memory unit after that sending and before receiving a response to the data from the other communication apparatus. When resending the data, resending processing to the other communication apparatus is performed based on the data transferred to the first memory unit.