A broadcast receiver, and a method of processing data are disclosed. The broadcast receiver includes a receiving unit, a RS frame decoder, a decoding unit, and an output unit. The receiving unit receives a broadcast signal multiplexed mobile broadcast service data including a first information associated with safety/security and main broadcast service data. The RS frame decoder performs CRC-decoding and RS-decoding on the RS frame, thereby correcting errors occurred in the corresponding mobile broadcast service data. The decoding unit extracts the first information from the error-corrected mobile broadcast service data, thereby decoding the extracted data with at least one of an audio decoder, a video decoder, and a data decoder. The output unit outputs the first information decoded by the decoder in a form of at least one of a text, a voice message, and an image.