A method of production of a multilayer circuit board comprising using a curable composition which contains a heat curable resin and curing agent (I) to form an uncured or semicured resin layer on a board (step A), then bringing a curing agent (II) able to substantially to cure the heat curable resin at a temperature at which the curing agent (I) cannot substantially cure the heat curable resin into contact with the surface of the resin layer, then heating the resin layer at a temperature at which the curing agent (I) cannot substantially cure the heat curable resin and the curing agent (II) can substantially cure the heat curable resin (step B), next heating and curing the resin layer at a temperature at which the curing agent (I) can substantially cure the heat curable resin to form an electrical insulating layer (step C).