Resistance to chestnut gall wasp (Dryocosmus kuriphilus) of Korean prevailing chestnut cultivars, newcultivars released by Korea Forest Research Institute (KFRI), and local cultivars by growers was investigated toselect optimal cultivars suitable for main chestnut producing areas. During three years investigated from 2004to 2006, we could find no damage by chestnut gall wasp in any cultivars of test sites located in Gongju andChungju of the central area. However, most cultivars of Gwangyang, Sancheong and Hapcheon sites located inregional damage by chestnut gall wasp. From comparison among cultivars, Kwangeun, Sandae, Eunsan and Idaereleased by KFRI showed no damage suggesting the highest resistant cultivars. On the contrary, over 20% intotal damage by chestnut gall wasp was investigated in Tanzawa, Riheiguri, Kurakata-amaguri, Pyeonggi,Gwangdeok, Seil, Sinipyeong and Yumabyuni suggesting susceptible cultivars. In damage by chestnut gal waspaccording to investigated position within tree, weak shoot was more severe than bearing shot. Damage bychestnut gall wasp of major cultivars in Gwangyang, Sancheong and Hapcheon sites was remarkably decreasedin 206, and it seems to be caused by biological control by natural enemies such as Torymus sinensis.