In the present paper, the inhibitory effects of Antimycin-A (Antipiriculin, AP), Blastmycin (BM), and Phenyl mercuric acetate (PMA) on the fundamental metabolic systems of P. oryzae are reported. The enzyme solution of P. oryzae was able to oxidize some organic acids found in TCA cycle, and this oxidation, especially that of succinate or lactate, was remarkably inhibited by AP, BM, and PMA. The endogenous respiration of the enzyme solution, however, was not inhibited by these inhibitors, but was inhibited by a high concentration of PMA. As to the terminal respiratory systems in P. oryzae, the following series of hydrogen doner and acceptor systems were presented, that is, succinic dehydrogenase, succinoxidase system, and cytochrome oxidase system. Both AP and BM showed definitely a specific inhibition to the succinoxidase system, whereas PMA inhibited all these systems. The oxidative phosphorylation and glycolysis in P. oryzae were also found not to be affected by AP and BM, although PMA seemed to inhibit the glycolysis slightly.