An electric supercharging device utilizing a waste heat of an internal combustion engine, comprising: a steam cycle device configured to rotate a steam turbine with a steam generated by a heat of an exhaust gas discharged from the engine; a first generating device configured to generate an electrical power by a torque of the steam turbine; a first battery which stores the electrical power generated by the first generating device; an electric supercharger comprising a motor configured to be driven by the electrical power of the first battery and configured to drive a first compressor to generate a compressed air, wherein the first battery stores the electrical power for driving the supercharger; a turbocharger comprising an exhaust gas turbine, configured to be driven by the exhaust gas, and a second compressor attached to the rotational shaft of the exhaust gas turbine and configured to pressurize intake air, wherein the compressed air discharged from the turbocharger is configured to be supplied to an intake side of the first compressor, thereby realizing two-stage supercharging of the engine; an exhaust gas processing device disposed on the downstream side of the turbocharger; and a wastegate valve disposed on an upstream side of the turbocharger in an exhaust gas system to adjust an amount of the exhaust gas introduced into the turbocharger, wherein the exhaust gas introduced into the turbocharger is configured to be introduced into the steam cycle device via the exhaust gas processing device, and the exhaust gas from the wastegate valve is configured to be introduced to the steam cycle device via a bypass line bypassing the turbocharger and the exhaust gas processing device wherein the electric supercharging device further comprises a power management system including said first battery, a second battery, an electronic control unit, ECU, configured to control the first and the second batteries (8, 81) and an interchange between the first and the second batteries (8, 81) while monitoring a state of charge, SOC, of each of the batteries (8, 11), and a bidirectional converter configured to interchange electrical power between the batteries (8, 81) based on an electrical power interchange command of the ECU, and wherein the power management system is configured to interchange electrical power from the first battery to the second battery when an amount of electric charge in the first battery is not less than an amount of electrical power for driving the motor by the first battery for obtaining a necessary compressed air in the first compressor. a steam cycle device configured to rotate a steam turbine with a steam generated by a heat of an exhaust gas discharged from the engine; a first generating device configured to generate an electrical power by a torque of the steam turbine; a first battery which stores the electrical power generated by the first generating device; an electric supercharger comprising a motor configured to be driven by the electrical power of the first battery and configured to drive a first compressor to generate a compressed air, wherein the first battery stores the electrical power for driving the supercharger; a turbocharger comprising an exhaust gas turbine, configured to be driven by the exhaust gas, and a second compressor attached to the rotational shaft of the exhaust gas turbine and configured to pressurize intake air, wherein the compressed air discharged from the turbocharger is configured to be supplied to an intake side of the first compressor, thereby realizing two-stage supercharging of the engine; an exhaust gas processing device disposed on the downstream side of the turbocharger; and a wastegate valve disposed on an upstream side of the turbocharger in an exhaust gas system to adjust an amount of the exhaust gas introduced into the turbocharger, wherein the exhaust gas introduced into the turbocharger is configured to be introduced into the steam cycle device via the exhaust gas processing device, and the exhaust gas from the wastegate valve is configured to be introduced to the steam cycle device via a bypass line bypassing the turbocharger and the exhaust gas processing device wherein the electric supercharging device further comprises a power management system including said first battery, a second battery, an electronic control unit, ECU, configured to control the first and the second batteries (8, 81) and an interchange between the first and the second batteries (8, 81) while monitoring a state of charge, SOC, of each of the batteries (8, 11), and a bidirectional converter configured to interchange electrical power between the batteries (8, 81) based on an electrical power interchange command of the ECU, and wherein the power management system is configured to interchange electrical power from the first battery to the second battery when an amount of electric charge in the first battery is not less than an amount of electrical power for driving the motor by the first battery for obtaining a necessary compressed air in the first compressor.