Provided is a curable composition for inkjet applied by an inkjet method, that has a long pot life even in the environment in an inkjet device warmed to 50° C. or higher and excellent insulation reliability by the cured product after curing despite containing a compound having a cyclic ether group. The composition for inkjet according to the present invention is applied by an inkjet method, and cures by heat addition, the composition for inkjet according to the present invention contains a compound having a cyclic ether group and a curing agent, and the curing agent is a reaction viscous product obtained by reacting dicyandiamide with a functional group-containing compound having a functional group reactive with the dicyandiamide.