A substrate transfer apparatus 100 includes a substrate transport means 4 having a transport base 5 and a plurality of retention arms 41a-41e for retaining substrates W, an optical sensor 62 that is used to define a horizontal optical axis L, an elevator means 52 for moving the transport base 5 up and down, and a height detection means 54 for detecting the height of the transport base 5 relative to the optical axis L. In accordance with a light-reception/no-light-reception detection result fed from the optical sensor 62 and the height of the transport base 5, a judgment means 72a of a control section 7 judges whether the postures of the retention arms 41a-41e relative to the horizontal plane are normal. When the judgment means 72a judges that the postures of the retention arms 41a-41e relative to the horizontal plane are abnormal, the control section 7 exercises control to stop the substrate transport means 4.