As preliminary research to clarify the metabolic pathway of L-ascorbic acid by micro-organism, the enzyme system concerning with the decomposition of L-ascorbic acid was investigated by experiments using inhibitors for various enzyme system. As the results of experiments, dehydrogenase system, enolase, Fe-containing enzyme, oxidative decarboxylation, and oxidative phosphorylation were presumed to participate in the decomposition of L-ascorbic acid by inhibition with ICH_2COOH(10^<-1>〜10^<-3>M), NaF(10^<-2>〜10^<-3>M), KCN(10^<-3>M), As_2O_3 (10^<-3>M) and NaN_3(10^<-3>〜l0^<-4>M) to L-ascorbic acid metabolism respectively. Moreover, the existence of TCA-cycle was also suggested by the experiments that resting cells of tested organism had the ability to oxidize some members of TCA-cycle and succinic acid and α-ketoglutaric acid oxidation were inhibited with malonate (10^<-3>M) and As_2O_3(10^<-3>M) respectively. From the above mentioned results, it was supposed that L-ascorbic acid was finally metabolized to CO_2 and H_2O through TCA-cycle. On the other hand, stimulative effects of some vitamins in the L-ascorbic acid metabolism by vitamin-deficiency cells led to the view that these vitamins were concerned with the co-factors of L-ascorbic decomposing enzyme system.