In a transmission apparatus, a first parity calculation controller calculates parity by the frame and inserts a calculation result into a next frame to a first frame sequence. A second parity calculation controller calculates the parity by the frame and inserts a calculation result into a next frame to a second frame sequence. The second parity calculation controller receives from the first parity calculation controller first parity data which is a parity calculation result by the first parity calculation controller and which has the same value as that of a parity calculation result to be inserted into a target frame of a parity calculation in the second frame sequence. Then, the controller calculates the parity of the target frame including the first parity data and second parity data which is a parity calculation result of a previous frame in the second frame sequence before one frame of the target frame.