The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for performing a random access procedure in wireless communication system, the method comprising: transmitting a random access preamble (RAP) on a physical random access channel (PRACH) resource in a radio frame; calculating a random access-radio network temporary identifier (RA-RNTI) by considering time-frequency resource associated with the PRACH resource and an index of a first radio frame of the PRACH resource; and monitoring a physical downlink control channel (PDCCH) identified by the calculated RA-RNTI for RAR reception during a RAR window.