The number of constituent components is reduced so as to provide a small-size and inexpensive electric-power conversion system. The electric-power conversion system is provided with an inverter circuit (14) connected with the rear stage of an AC power source, a smoothing capacitor (22) connected with the rear stage of the inverter circuit (14) by way of a rectifying device (20), a charging switch (2) that is connected with the front stage of the inverter circuit (14), that inputs an electric quantity based on an output of the AC power source (1) to the inverter circuit (14) when being turned on, and that cuts off an input of the electric quantity to the inverter circuit (14) when being turned off, and an inrush current prevention circuit (7) having an inrush current prevention switch (3) and an inrush current prevention resistor (4) that is connected in series with the rear stage of the inrush current prevention switch (3); the electric-power conversion system is characterized in that the inrush current prevention circuit (7) is connected in parallel with the charging switch (2).