A green smart factory energy management system for carbon reduction, includes: an eco-friendly power generator installed on one side of a building to generate first electrical energy through wind power or sunlight; a water electrolysis device for receiving surplus power of the first electrical energy remaining after operating a building, and electrolyzing water to generate hydrogen; a hydrogen storage device for storing some of the hydrogen generated by the water electrolysis device; a hydrogen fuel cell for generating second electrical energy by using some of the hydrogen generated by the water electrolysis device; a machine tool provided with an electrically driven spindle system to grip or rotate a workpiece when the second electrical energy is applied; and a distributed power management device for controlling an amount of power consumed.