Outline of this report was presented as communication to Editor in this journal. New toxic substances, m.p. 188∼188.5°C, C29H47O7N5 and m.p. 234°C, C25H42O6N4 were isolated from the active syrup extracted from the culture filtrate and the fungal mats of Oospora destructor (METCH.) DEI.AC. and they are named destruxin A and B, respectively. Destruxin A and B showed the strong toxicity to silkworms and mice by injection, but the toxicity to the potato lady beetles by the feeding was not so strong as in the case of the injection.