A method for monitoring a physical downlink control channel (PDCCH) by a user equipment (UE) in a wireless communication system is disclosed. The method comprises steps of receiving configuration information of a short discontinuous reception (DRX) cycle and a long DRX cycle from a network, wherein the configuration information includes information about a first ON duration for the short DRX cycle and a second ON duration for the long DRX cycle; and monitoring the PDCCH during the first ON duration using the short DRX cycle or during the second ON duration using the long DRX cycle according to the configuration information, wherein the length of the second ON duration is shorter than the length of the first ON duration.