A powder filling nozzle is used for filling up a container with a powder mixed with a gas and in a fluidized state. The power filling nozzle comprises a tubular body having an opening for discharging the powder in the fluidized state into the container, and a gas separating unit disposed near the opening of the tubular body and allowing the gas delivered together with the powder in the tubular body to pass through the gas separating unit but not allowing the powder to pass through the gas separating unit. The gas separating unit serves to set the opening in a plugged state by the powder separated from the gas, so that the delivery of the powder from the tubular body into the container is stopped.