To explain the change of the pungent principles of red pepper, capsaicin, during storage, the relation between infecting mold and capsaicin was studied. Results obtained were summarized as follows; 1. Superior strains which showed good growth and high decomposition activity in their culture broths, Aspergillus oryzae and Aspergillus sp. KF-7 were obtained from the contaminated red pepper fruits. 2. The weight of dry matter was increased at low concentration of capsaicin $(2{sim}3{mu}g/ml)$ but it was decreased at high concentration. 3. The residual capsaicin in the culture medium was reduced as half as such after 1 week, and almost disappeared after 2 weeks. At $30^{circ}C$ and $pH;7{sim}9$ of culturing condition, the amounts of reducing capsaicin reached to the maximum. 4. At ground red pepper fruits as culture medium, Aspergillus sp. KF-7 could not glow at all, but Aspergillus oryzae showed good growth at 13% of moisture contents and the residual of capsaicin of red pepper fruits after 40days of cultivation time was 45%. 5. At ground red pepper fruits seed as culture medium, Aspergillus oryzae and Aspergillus sp. KF-7 showed good growth, and the residual of capsaicin after 4 weeks of cultivation time was 55% and 38% respectively.