An apparatus and a method for transmitting/receiving data generate main service data of broadcasting data, generate additional data of the broadcasting data, transform the additional data into a parallel type, generate pseudo-random noise sequences as a spreading code of the additional data, select polarities of the pseudo-random noise sequences using any one additional data bits in the additional data in the transformed parallel type, map the remaining additional data bits excluding the one additional data bit from the additional data in the transformed parallel type to a single sequence, multiply a single sequence to which the remaining additional data bits are mapped by pseudo-noise sequences of which the polarities are selected, control mean power of the additional data multiplied by the sequences, couple the additional data of which the mean power is controlled with the main service data, and then, transmit the broadcasting data.