It is intended to provide the following resin composition for stereolithography which is superior in storage stability and aging stability during operation, shows no increase in viscosity upon prolonged storage, has a high light-curing sensitivity and, therefore, makes it possible to produce, upon photo irradiation, an object by stereolithography, which is superior in dimensional accuracy, fabricating accuracy, water resistance, moisture resistance and mechanical properties at a high fabricating speed and a high productivity. A resin composition for stereolithography which is an actinic radiation-curable resin composition containing a cationic-polymerizable organic compound, a radical-polymerizable organic compound, a photo cationic polymerization initiator and a photo radical polymerization initiator, in which the photo cationic polymerization initiator contains a compound represented by the following formula (I) and having a purity of 80% or higher: wherein M represents an antimony atom or a phosphorus atom; and the broken line between S+ and MF6− represents an ionic bond.