A transmitting apparatus comprising: a frame encoder configured to Reed Solomon encode a plurality of frames to generate RS-encoded frames, wherein the frame encoder is configured to divide the plurality of frames into a plurality of groups and RS encode each group to generate the RS-encoded frames, the encoding is performed in a vertical direction with reference to a horizontal direction of the plurality of frames, further comprising: a forward error correction encoder configured to FEC encode the RS-encoded frames; a constellation mapper configured to map bits of the FEC-encoded frames onto cells; and a time interleaver configured to interleave the cells, wherein, if a number of the RS-encoded frames is greater than a maximum number of frames that can be generated by the RS encoding in a predetermined Galois field, the frame encoder is configured to determine a number of the plurality of groups based on a number of the RS-encoded frames and a maximum number of frames that can be generated by the RS encoding in the predetermined Galois field, and divide the plurality of frames into the plurality of groups based on the determined number, wherein the frame encoder is configured to calculate a number of the groups to divide the plurality of frames using a mathematical formula as below: B = ⌊ N N ′ ⌋ + 1. where B is the number of the groups to divide the plurality of frames, N is the number of frames to be RS encoded by the frame encoder, and N' is the maximum number of frames that can be generated by RS encoding which is defined in the predetermined Galois field. a frame encoder configured to Reed Solomon encode a plurality of frames to generate RS-encoded frames, wherein the frame encoder is configured to divide the plurality of frames into a plurality of groups and RS encode each group to generate the RS-encoded frames, the encoding is performed in a vertical direction with reference to a horizontal direction of the plurality of frames, further comprising: a forward error correction encoder configured to FEC encode the RS-encoded frames; a constellation mapper configured to map bits of the FEC-encoded frames onto cells; and a time interleaver configured to interleave the cells, a forward error correction encoder configured to FEC encode the RS-encoded frames; a constellation mapper configured to map bits of the FEC-encoded frames onto cells; and a time interleaver configured to interleave the cells, wherein, if a number of the RS-encoded frames is greater than a maximum number of frames that can be generated by the RS encoding in a predetermined Galois field, the frame encoder is configured to determine a number of the plurality of groups based on a number of the RS-encoded frames and a maximum number of frames that can be generated by the RS encoding in the predetermined Galois field, and divide the plurality of frames into the plurality of groups based on the determined number, wherein the frame encoder is configured to calculate a number of the groups to divide the plurality of frames using a mathematical formula as below: B = ⌊ N N ′ ⌋ + 1. where B is the number of the groups to divide the plurality of frames, N is the number of frames to be RS encoded by the frame encoder, and N' is the maximum number of frames that can be generated by RS encoding which is defined in the predetermined Galois field.