A method for determining a transport block size and a signal transmission method using the same are disclosed. When the signal transmission method constructs a transport block size combination by predetermining the transport block size, it prevents the insertion of any dummy bits in consideration of the limitation of an input bit length of an encoder during an encoding step. If a CRC is attached to the transport block and the transport block is segmented into a plurality of code blocks, the signal transmission method can establish a length of the transport block in consideration of a length of the CRC attached to each code block.