Disclosed are a method and an apparatus for transmitting data in device to device (D2D) communication. A method for transmitting data in D2D communication can comprise the steps of: a first device generating first D2D data in a TB unit; and the first device transmitting to a second device only the first D2D data on one or more D2D communication resources on the basis of a sub-RPT, wherein the sub-RPT is comprised in an RPT defined on a D2D resource pool and can indicate one or more D2D communication resources for transmitting only the first D2D data on a plurality of D2D communication candidate resources.