According to one embodiment, a method of processing a digital broadcasting signal in a transmitter includes: performing RS (Reed-Solomon) encoding on signaling data containing cross layer information between a physical layer and a upper layer; interleaving the RS encoded signaling data, wherein interleaving the RS encoded signaling data includes writing the RS encoded signaling data row-by-row from left-to-right and top-to-bottom in a signaling data block, and outputting the signaling data in the signaling data block by reading column-by-column from top-to-bottom and left-to-right; and transmitting the digital broadcasting signal including the mobile service data and the interleaved signaling data during slots.