The structure of sclerotiorin, C₂₁H₂₃O₅Cl, found in the metabolic product of Penicillium implicatum was discussed. Sclerotiorin reacted with ammonia and changed to sclerotioramine (II). From the acetate of (II), 2, 4, 5-pyridinetricarboxylic acid was obtained by treatment with ozone, followed by potassium permanganate. Tetrahydrosclerotiorin was degradated by alkali to a quinone compound which was determined as β-dihydroxynaphthoquinone. The relation of substituted groups (OH, OH, Cl, CH₃) in aposclerotioramine (IV) was cleared and a tentative structural formula (I) is forwarded for sclerotiorin.