Disclosed is heat curing rubber clay for handicrafts. The invention of this clay with added platinum hardening agent is to create projects and use as custom toys that is hardened and elastic by being heated in the oven. To this end, the heat curing rubber clay for handicrafts according to the present invention contains 60 to 80% by weight of a gel-type silicone base, based on the total weight of the rubber clay, wherein the gel-type silicone base consists of a mixture of siloxanes and silicones, dimethyl, methylvinyl, and vinyl group-terminated; 15 to 35% by weight of a plasticity adjuster, based on the total weight of the rubber clay, wherein the plasticity adjuster contains powder-type silica to control hardness; 1 to 5% by weight of an oil-type anti-cracking agent, based on the total weight of the rubber clay, consisting of polydimethylsiloxane to prevent cracking; 0.1 to 1% by weight of an antimicrobial agent to prevent propagation of bacteria; and 0.65 to 5% by weight of a platinum hardening agent.