380keV proton irradiation effects are investigated on p-GaN and n-GaN layers in GaN-based light emitting diode (LED) by characterizing current-voltage (I-V) characteristics of p-n junction, and two-terminal resistance of p- and n-GaN on both type of layers in LED wafer. Two-terminal resistance on n-GaN kept its initial value after the 1×1014cm-2 fluence, and was remained the same order after the 1×1015cm-2 fluence. On the other hand, p-GaN showed sensitive increase in two-terminal resistance after the 1×1014cm-2, and six orders of increase after the 1×1015cm-2 fluence. Observed sensitive increase of resistivity in p-GaN is explained as a lower initial hole density in p-GaN than the initial electron density in n-GaN layer.