To provide an epoxy resin composition for sealing photosemiconductor in which heat resistance to soldering is increased by reduction of hygroscopicity and raising of Tg while keeping transparency which is a basic performance.

The epoxy resin composition for sealing photosemiconductor consists essentially of an epoxy resin, a curing agent and a curing accelerator. At least either one curing agent of acid anhydride type curing agents represented by chemical formula A (wherein R is -CH3, -H or -CH2CH3; n is 0-4) and chemical formula B (wherein n is 0-4) is used as the curing agent. The epoxy resin composition can lower moisture absorption of the cured product and increase the glass transition temperature (Tg) of the cured product while keeping transparency of the cured product and has enhanced heat resistance to soldering.