The present invention relates to a method for electricity measurement by a vehicle-to-vehicle (V2V) device for V2V communications in a wireless communication system and to a device therefor. In particular, the present invention includes the steps of: receiving at least one synchronization signal for V2V through a physical sidelink broadcast channel (PSBCH); and measuring received electricity from said at least one synchronization signal if the ID of said at least one synchronization signal is linked to a demodulation reference signal (DMRS) sequence having, applied thereto, an orthogonal cover code (OCC) having one fixed value, wherein the measurement is performed by means of averaging for each ID of said at least one synchronization signal.