The present invention relates to a wireless communication system. More specifically, the present invention relates to a method and a device for transmitting an UL packet delay measurement report in a wireless communication system, the method comprising: receiving a measurement configuration including a measurement period and a plurality of sample thresholds configured for each QCI from an eNB, performing an UL packet delay measurement for a QCI based on queuing delays of a plurality of PDCP SDUs from radio bearers associated with the QCI during the measurement period, checking whether a number of the plurality of PDCP SDUs is larger than a sample threshold configured for the QCI among the plurality of sample thresholds, and transmitting an UL packet delay measurement report for the QCI including the QCI and a result of the UL packet delay measurement for the QCI to the eNB, if the number of the plurality of PDCP SDUs is larger than the sample threshold configured for the QCI.