To provide production methods for a 3-D mold, a finely processed product, and a fine pattern molded product in which the depth and the line width can be formed with high precision, a 3-D mold, a finely processed product, a fine-pattern molded product, and an optical element formed with high precision.A method of producing a 3-D mold that is configured to control depth within 10 nm and form a line width of 200 nm or less, wherein an irradiation step, which irradiates an electron beam to a resist layer of an object of processing that has the resist layer constituted with a polysiloxane-based material on or above a substrate, includes a step having irradiation conditions such that the acceleration voltage is from 1 kV to 3 kV without generation of the backscattering and the dosage is 400 .mu.C/cm.sup.2, a method of producing finely processed product using the 3-D mold, a method of producing fine-pattern molded product using the 3-D mold or the finely processed product, and the 3-D mold, the finely processed product, the fine-pattern molded product, and an optical element formed with high precision with these production methods.