This invention relates to a silicone resin composition which exhibits high heat resistance, high transparency and high dimensional stability and thus can be suitably used for optical applications such as a lens, an optical disc, an optical fiber, a substrate for a plat panel display, a window material for an automobile, and the like. A silicone resin composition, which comprises a silicone resin comprising, as a primary component, a polyorganosilsesquioxane being represented by the formula: [RSiO3/2]n, wherein R represents an organic functional group having a (meth)acryloyl group, and n is 8, 10 or 12, and having a cage type structure in its structural unit, and an unsaturated compound having, in its molecule, at least one unsaturated group represented by —R3—CR4═CH2 or —CR4═CH2, wherein R3 represents an alkylene group, an alkylidene group or a —OCO— group and R4 represents a hydrogen atom or an alkyl group, and being capable of radically copolymerizing with the above silicone resin, in a weight proportion of 1:99 to 99:1.