Abstract: A method for operating a dust collection device by reducing the adhesion of high-resistance dust while performing stable charging, with minimal pressure loss and high efficiency. The dust collection device comprises a pre-charging unit and a bag filter in a flue gas duct through which a gas flows, with the pre-charging unit disposed upstream from the bag filter, wherein the pre-charging unit comprises electrodes that charge the dust, a power source that supplies electric power to the electrodes, and a gas flow rate control device that adjusts the flow rate of the gas flowing through the pre-charging unit to a prescribed value. The method comprises a step of charging the dust by applying a voltage from the electrodes to the dust, and a step of removing the dust adhered to the electrodes by increasing the flow rate of the gas flowing through the pre-charging unit.