A contact charging method for an electric vehicle, comprising the steps of: providing a power supplying device, which includes a power line retaining part in which a V-shaped groove is provided that faces toward a side portion of the electric vehicle and is formed to open in upper and lower directions of the electric vehicle and to extend in a running direction of the electric vehicle, and in which a positive electrode power line on one inner surface and a negative electrode power line on another inner surface of the V-shaped groove of the power line retaining part are fixed to the power line retaining part respectively along the running direction and at positions to maintain an insulation distance mutually therebetween; providing a charging arm accommodated in the side portion of the electric vehicle, the charging arm including on its distal end a positive electrode power reception unit and a negative electrode power reception unit, which are disposed so as to face the corresponding positive electrode power line and the corresponding negative electrode power line of the power supplying device, shaping the positive electrode power reception unit and the negative electrode power reception unit into rolling wheels rolling by contact with the power supplying device; when extending the charging arm out in a vehicle widthwise direction to press the V-shaped groove, the distal end of the charging arm is positioned away from a bottom of the V-shaped groove, while bringing into contact simultaneously the positive electrode power line of the power supplying device and the positive electrode power reception unit of the charging arm, and the negative electrode power line of the power supplying device and the negative electrode power reception unit of the charging arm, and charging an electrical storage device for driving of the electric vehicle; and arranging respective surfaces of the positive electrode power reception unit and the negative electrode power reception unit in contact with the positive electrode power line and the negative electrode power line to be inclined with respect to an axis of the positive electrode power reception unit and the negative electrode power reception unit, the axis extending in a direction perpendicular to a longitudinal direction of the charging arm. providing a power supplying device, which includes a power line retaining part in which a V-shaped groove is provided that faces toward a side portion of the electric vehicle and is formed to open in upper and lower directions of the electric vehicle and to extend in a running direction of the electric vehicle, and in which a positive electrode power line on one inner surface and a negative electrode power line on another inner surface of the V-shaped groove of the power line retaining part are fixed to the power line retaining part respectively along the running direction and at positions to maintain an insulation distance mutually therebetween; providing a charging arm accommodated in the side portion of the electric vehicle, the charging arm including on its distal end a positive electrode power reception unit and a negative electrode power reception unit, which are disposed so as to face the corresponding positive electrode power line and the corresponding negative electrode power line of the power supplying device, shaping the positive electrode power reception unit and the negative electrode power reception unit into rolling wheels rolling by contact with the power supplying device; when extending the charging arm out in a vehicle widthwise direction to press the V-shaped groove, the distal end of the charging arm is positioned away from a bottom of the V-shaped groove, while bringing into contact simultaneously the positive electrode power line of the power supplying device and the positive electrode power reception unit of the charging arm, and the negative electrode power line of the power supplying device and the negative electrode power reception unit of the charging arm, and charging an electrical storage device for driving of the electric vehicle; and arranging respective surfaces of the positive electrode power reception unit and the negative electrode power reception unit in contact with the positive electrode power line and the negative electrode power line to be inclined with respect to an axis of the positive electrode power reception unit and the negative electrode power reception unit, the axis extending in a direction perpendicular to a longitudinal direction of the charging arm.