Provided is a curable composition capable of giving a lens that has excellent transfer accuracy from a mold and offers heat resistance and optical properties at excellent levels. The curable composition according to the present invention for lens formation contains a cycloaliphatic epoxide (A) represented by Formula (a), a cationic-polymerization initiator (B), and a polysiloxane (C) represented by Formula (c). The curable composition contains the polysiloxane (C) in an amount of 0.01% to 5% by weight based on the total amount of the curable composition. The curable composition according to the present invention for lens formation may further contain a siloxane compound (D) containing two or more epoxy groups per molecule.