PURPOSE: To obtain the insulated coil having excellent heat-resisting life by using a maleimide compound, cyanic acid ester, an epoxy compound and a polyvalent carboxylic acid arylester compound as the principal ingredients for the resin of the insulated coil constituting a resin layer.

CONSTITUTION: A heat-resisting sheet material, such as an aromatic polyamide nonwoven fabric, a polyamide film, a polyimide film, a mica tape or the like, the maleimide compound, such as a N, N'-substituted dimaleimide compound, a low melting-point maleimide compound or the like, the cyanic acid ester consisting of an aromatic compound with not less than two cyanic acid ester groups, the epoxy compound, such as bisphenol A type, F type, phenol novolac type or the like, and the polyvalent carboxylic acid arylester compound, such as an aromatic compound with not less than two aryl groups, a triazine cyclic compound or the like are used as the principal ingredients and combined. Accordingly, the insulated coil, which is electrically and mechanically balanced and has excellent characteristics and heat-resisting life, can be obtained.