Disclosed is a position detecting apparatus for detecting a relative position of two objects which are relatively moved. The apparatus includes a probe, a probe driving device, a position detecting device and an object driving device. The probe is provided for the first of the two objects so as to face the surface of the second of the two objects, so as to read information from the surface of the second object. The probe driving device allows the probe to two-dimensionally scan the surface of the second object so that the probe reads the two-dimensional information from the surface of the second object. The position detecting device detects a relative positional relation of the two objects by comparing the two-dimensional information obtained by the two-dimensional scan of the probe by the probe driving device with reference to two-dimensional information. The object driving device executes the relative positioning of the two objects on the basis of the result of the detection of the position detecting device.