To obtain a resin composition for photosemiconductor sealing, which can give a cured product excellent in transparency and mold release by mixing an epoxy resin with an acid anhydride curing agent, a specified mold release and a cure accelerator.

This resin composition for photosemiconductor sealing comprises an epoxy resin, an acid anhydride curing agent, a mold release represented by the formula: C17H35COOX (wherein X is a hydrogen, an alkyl, its derivative or a metallic element) and an cure accelerator. The mold release is desirably used in an amount of 4-10wt.% based on the entire resin composition. The mold release is desirably one represented by the formula (wherein X is propyl or 2-hydroxypropyl).