To increase the effectiveness of a dc high-tension cable for use as the high-tension lead wire of a television set or high-tension wiring for electronic equipment by making it excellent in heat-resistant aging characteristic without lowering its initial breakdown voltage.

An insulating layer is formed by covering a conductor 1 with a resin composition with which the peak value of the amount of a space charge accumulated by the irradiation of an electron ray with a quantity of irradiation of 30 to 500kGy is in the range 0 to 100μC/cm3 as measured using pulse electrostatic stress method; and a flame-resistant sheath layer 3 is formed on the outer periphery of the insulating layer to obtain a dc high-tension cable, at least the insulating layer of which is irradiated with electron rays. To the insulating layer 2 is added an oxidation inhibitor in which a polyethylene has two or more hindered phenol groups and/or semi-hindered phenol groups in its molecules or has an amide group and/or a hydrazine group in addition to them, with a total molecular weight of 500 or more and with either the molecular weight of molecular chains in the molecules being not less than 100 or the number of atoms in the principal chains of the molecules being not less than 6 not more than 30.