The present invention relates to a method and apparatus for transmitting a Device-to-Device Synchronization Signal (D2DSS) for D2D communication by a terminal in a wireless communication system and, more particularly, comprises a step of transmitting a D2DSS, wherein first root indexes associated with the D2DSS are set to be different from second root indexes associated with sync signals for a cellular communication, and the number of the first root indexes is less than the number of the second root indexes.