A semiconductor processing system includes a transfer apparatus for transferring a wafer. The transfer apparatus has a pick arm member with wings. The reference distances between the wafer located at the normal position and the wings are stored in a memory of a CPU. Detection ranges of line sensors are set in a standby position in front of a process chamber in order to detect the distances between the wafer and the wings. In the CPU, the amount of positional shift of the wafer is detected based on the reference distances and the detected distances.