The present invention relates to a method for performing uplink transmission to a base station through an unlicensed cell in a wireless communication system, in particular, the invention provides a method including: receiving, from the base station, an uplink grant scheduling the uplink transmission on one or more subframes; and performing the uplink transmission on the one or more subframes using one of a first type channel access or a second type channel access indicated in the uplink grant, wherein a parameter for the first type channel access is determined according to a priority included in the uplink grant, and wherein when the uplink grant indicates the second type channel access, the priority is a priority used in a downlink channel access of the base station.