This method for manufacturing an electroseamed metal tube is for manufacturing an electroseamed metal tube by abutting the side ends of a metal strip and then welding the side ends by high frequency heating. An inner-surface-side corner positioned on the inner surface side of the electroseamed metal tube is provided on the side end. The method includes a step for forming a slanted surface on the inner-surface-side corner before abutting the side ends of the metal strip. The side ends are abutted and welded such that the slanted surface remains on the excess metal of the metal tube after electric welding and such that the discharge metal is not welded with the excess metal.