Provided is a method for transmitting a broadcast signal, including: formatting input streams into multiple data pipes (DPs); encoding data of the multiple DPs for each DP; generating at least one signal frames by mapping the encoded data; and modulating data of the generated signal frame using an orthogonal frequency division multiplexing (OFDM) scheme and transmitting a broadcast signal comprising the modulated data of the signal frame, wherein the signal frame includes a preamble, a PLS (Physical Layer Signaling) and EAC (Emergency Alert Channel), the preamble and the PLS include EAC flag information indicating whether there exists EAC in the signal frame, and when the EAC flag information indicates that there exists EAC in the current frame, the PLS further comprises EAC length information, and when the EAC flag information indicates that there doesn't exist EAC in the current frame, the PLS further comprises control information related to EAC transmission.