A method for transporting a cassette pod for containing semiconductor waters is provided. The method includes transporting a cassette pod configured to receive a semiconductor wafer with a transporting apparatus. The method further includes supplying a gas from a cylinder into a housing of the cassette pod. The cylinder is externally positioned on the housing. The method also includes detecting a gas pressure in the cylinder with a detection element. In addition, the method includes issuing a signal to the transporting apparatus when the gas pressure in the cylinder is lower than a predetermined limit.