A method of monitoring a control channel in a wireless communication system includes monitoring a physical down-link control channel (PDCCH) during a monitored duration, wherein the monitored duration is a part of a discontinuous reception (DRX) period, the DRX period specifying the periodic repetition of the monitored duration followed by a non-monitored duration. By monitoring a control channel during a DRX period, battery consumption of a user equipment can be reduced and an operation time of the user equipment can be increased.