To provide a method of precisely teaching a wafer position, without making a processing device interfere, even if the frontage of the processing device is narrow, and to provide an external teaching jig therefor.

In the method of teaching a wafer position by a wafer transfer device, a teaching jig 16 is set at a position of the storage containers or processing devices where a semiconductor wafer is placed, and a sensor provided at a wafer holding unit of a robot which transfers the semiconductor wafer, between the storage container and processing device or between the processing devices, detects the teaching jig. Thus, the robot is made learn the position of a semiconductor wafer. In the method, before sensing the teaching jig 16, the sensor senses an external teaching jig 17 which is set at the front wall of the processing device, and estimates roughly the position of the teaching jig. Then, the sensor approaches to sense the teaching jig, based on the estimated position and obtains the position of the semiconductor wafer.