Disclosed herein are a method and apparatus for sending and receiving data in a wireless communication system. More specifically, a method for sending and receiving, by UE, data in an unlicensed band in a wireless communication system may include performing blind detection for detecting a predetermined specific signal transmitted by an eNB in a cell of an unlicensed band and determining a period in which the signal is detected through the blind detection to be a reserved resource period (RRP) which is a time period secured for the transmission and reception of data in the cell of the unlicensed band.