This study was investigated the growth characteristics of ‘Nongjingo’ cultivar(Lentinula edodes) according to relative humidity(RH). The color difference of the pileus showed the highest L(Lightness, L) value in RH65 and the a(Redness, a) value in RH95. b(Yellowness, b) values were similar in all treatments. The hardness of pileus is highest at RH95. As the relative humidity increased, the length of pileus and stipe tended to increase. The diameter and thickness of pileus were high at RH95%. The diameter of stipe could not see the big difference in the three treatment groups. This study growth characteristics and yield were increased at higher relative humidity, but quality was decreased. Therefore, must adjust the relative humidity to produce high quality mushrooms.