Abstract: The invention relates to a power cord having an insertion plug at one end of a cord, and its manufacturing method, more particularly to a power cord and its manufacturing method high in reliability in tracking resistance, free from deviation of blade interval in forming process or plugging and unplugging operation, and excellent in heat resistance and tracking resistance: more specifically, the power cord is composed by connecting blades to plural conductors exposed at the end of cord, holding these blades at a specified interval spacing, and covering the base side and leading end side of cord with synthetic resin to form a plug, characterized by inserting the base of blades or from the base to the leading end of cord at a specified spacing distance, and ejecting and forming a core by hard thermoplastic resin such as polyamide, polybutadiene, or polypropylene, and inserting the core, and ejecting and forming a plug by a soft thermoplastic resin.