manner according to the above processes it is possible to carry a semiconductor substrate 36 to be processed in and to carry a processed semiconductor substrate 36 out by one extending and contracting operation of the extensible arm 35 of the semiconductor substrate transport arm that is one opening and closing operation of the gate of the semiconductor substrate processing chamber fig5 illustrates another embodiment of the present invention substrate holding portions 23 and 24 on first and second arms 21 and 22 are integrally formed and space apart from each other by 180 u00b0 through the turn axis center and mounted to a single rotary shaft 27 supported by a bearing 25 and having a pulley 26 although a semiconductor substrate processing chamber this embodiment must be larger than the chamber in the above embodiment in order to turn the first and second arms 21 and 22 in the same direction in the substrate processing room the structure of the semiconductor substrate transport arm is simple and the size of a gate of the semiconductor substrate processing room may be the same as that of the first embodiment according to the present invention since the positions of the semiconductor substrate holding portions that is pans disposed at the leading end of the extensible arm can be switched by sequentially turning the semiconductor substrate holding portions it is possible to carry a processed semiconductor substrate out of the processing chamber and carry.