In this study, wave energy resource in the northeast Asia has been assessed using the numerical simulation for 5 decades. For this purpose, wind field of JRA-55 has been used to force SWAN model for 1958-2012 in the northeast Asia with the boundary condition provided by a global model forced with the same wind field. The model was validated using satellite data and buoy measurements and was performed for the whole period. Based on the highest amount of energy, lowest intra-annual variability and lowest long-term change, the most suitable area in Japan for wave energy extraction is specified.