To provide an electromagnetic coil that can be used for a long period in an electric motor, solenoid-controlled valve, electromagnetic actuator, etc. This electromagnetic coil is composed of a coil bobbin 3, a coil 4, and a coil case 5. The coil 4 is sealed with a molding resin. Recessed sections 22a, 22b, 22c, 22d, etc., up to the outer peripheral surfaces 25a, 26a, etc., of a core 20 are formed on the internal side faces of the flanges 21a and 21b of the coil bobbin 2. In addition, the molding resin 6 which seals the periphery of the winding 4 is packed in the internal space between the flanges 21a and 21b of the bobbin 2 and the coil case 5, recessed sections 22a, 22b, 22c, 22d, etc., of the flanges 21a and 21b, and the space (not shown in the picture.) formed between the outer peripheral surfaces 25a, 26a, etc., of the core 20 and the coil 4 through vacuum defoaming treatment using the casting method.