It was investigated the possibility to use charcoal powder as beneficial soil conditioner, which used frequently in environmentally friendly agricultural farming system. For this purpose, the effects of charcoal powder on the growth of red pepper and chemical and microbiological properties of soil were also determined. The application of charcoal powder resulted in no significant differences of pH and EC in the soil compared to those of control. However, small particle size of charcoal powder increased yield of red pepper while large charcoal powder resulted in decrease of root growth of red pepper. Furthermore, the application of charcoal powder resulted in changes of soil microflora relating to plant growth stage. The number of the nitrogen fixing bacteria and fungi increased at the early growth stage, while phosphate releasing fungi in the soil increased at the late stage of growth by charcoal powder application. These beneficial effect of charcoal powder on the soil microbial properties was larger by the use of smaller particle size of charcoal powder. Therefore, it indicated that the small size of charcoal powder might be more influential on the red pepper yield and soil microbial properties may be due to large capacity of nutrients uptake for the plant and microorganisms. Additionally the optimal application amount of charcoal powder for the red pepper could be suggested as much as 300㎏ 10a⁻¹ for the both purposes of improvement of crop yield and retardation of the nutrients accumulation by excess charcoal application.