Disclosed are a broadcast signal transmitting apparatus, a broadcast signal receiving apparatus, and a method for transceiving a broadcast signal in a broadcast signal transceiving apparatus. A method for transmitting a broadcast signal comprises the following steps: performing MIMO encoding on a first input signal which is mapped to a first QAM type symbol and a second input signal which is mapped to a second QAM type symbol to output a first transmission signal and a second transmission signal; mapping the first transmission signal to a different subcarrier location for each cell unit while maintaining the bandwidth of a sub-band in a first signal frame constant, and mapping the second transmission signal to a different subcarrier location for each cell unit while maintaining the bandwidth of a sub-band in a second signal frame constant; inserting a pilot signal of a pilot pattern determined on the basis of FFT size information into a first signal frame to which the first transmission signal is mapped, and inserting first and second preamble signals into a starting point of the first signal frame to which the pilot signal is inserted; and inserting a pilot signal of a pilot pattern determined on the basis of FFT size information into a second signal frame to which the second transmission signal is mapped, and inserting first and second preamble signals into a starting point of the second signal frame to which the pilot signal is inserted.