Abstract: The present invention relates to a method and a device for allowing a transmitting device to transmit/receive data to/from a receiving device in a wireless communication system. According to the present invention, provided are a method and a device, the method: re-configuring specific data in a second layer of the first transmitting device on the basis of a resource allocation amount delivered from a first layer of the first transmitting device; generating at least one replicate data according to the number of a plurality of wireless bearers by using the re-configured specific data in the second layer; and transmitting, to the receiving device, the re-constructed specific data and the at least one replicate data from a plurality of cells related to the plurality of wireless bearers, wherein the plurality of wireless bearers are instructed by bearer identifiers to transmit the replicate data.