A resin composition for three-dimensional object by optical stereolithography containing a colorant, such as carbon black, in an amount of 0.05 to 0.5% by weight can provide a colored three-dimensional object which has excellent physical and mechanical properties such as dimensional accuracy, shape stability, hardness and tensile strength and elastic modulus in tension, as well as light-shielding properties, gives a massive impression and is colorful at a high optical shaping speed and in a good productivity.