A photosensitive resin composition comprising an isocyanurate-modified silicone resin containing an epoxy group in the molecule is easy to form a resin coating which has high transparency, light resistance and heat resistance, is amenable to micro-processing, and is useful in applications for protecting and encapsulating optical devices. The coating can be processed in thick film form to define a pattern having a fine size and perpendicularity, and becomes a cured coating which has improved adhesion to substrates, electronic parts, semiconductor devices, and supports for circuit boards, mechanical properties, electric insulation, and crack resistance, and is reliable as an insulating protective film.