Provided are: a curable composition from which a cured article having excellent molding processability and high heat resistance as well as such a high Tg that it can be used as a molding resin for a SiC power semiconductor can be obtained; and a cured article thereof. The curable composition comprises: 100 parts by mass of a compound having at least two partial structures represented by the following Formula (1) in the molecule as a component (A); 0.5 to 3 parts by mass of a thermal radical generator as a component (B); and 0 to 50 parts by mass of other radical-reactive compound as a component (C): (wherein, ring A represents a benzene ring or a cyclohexyl ring; R1 represents an alkylene group having 1 to 6 carbon atoms; R2 represents an alkyl group having 1 to 4 carbon atoms; a represents a number of 0 or 1; b represents an integer of 0 to 3; and c represents a number of 1 or 2).