PURPOSE: To increase a flashover point by covering and integrally sealing a metal terminal and the surface of a lead wire which passes through a cylindrical celamic located in a projected section of a bushing, with an insulation layer consisting of a resin material that has a high specific dielectric constant.

CONSTITUTION: A metal terminal 4 is fixed by means of a nut in a high voltage bushing 3 at its outer side projected section. One end of a lead wire 7 is connected to the inner side of the terminal 4 through a cylinder of an inner side projected section 6 of the bushing 3; the other end of the wire is to be connected to a coil. The surface of the lead wire 7 in the inner side projected section 6 of the bushing 3 and its extended area, and a jaw section 9 of the metal terminal 4 are integrally molded with a resin insulation layer 12 which is a flexible and relatively high specific dielectric constant material such as vinyl chloride. Then an oil inpregnated insulation tube 8 made of a tubularly coiled insulation paper is inserted in such a way that it covers the lead wire 7.