If a master device in device-to-device direct communication designates an object type of a target to be communicated with, transmits a target discovery request message including the object type of the target to be communicated with to a plurality of neighboring target devices, and receives a target discovery response message from one or more target devices corresponding to the object type of the target to be communicated with among the plurality of target devices, the master device determines one target device among one or more target devices as the target to be communicated with.