An exposure apparatus which exposes a second object with a pattern formed on a first object, comprising:
- a mark detecting device, which includes a photoelectric sensor, and which detects position information on a plurality of marks on said first object based on outputs of the photoelectric sensor, and
- a calculating device, which is electrically connected to said mark detecting device, which has one computer equation, and which obtains a plurality of error parameters by performing a statistical calculation using the computer equation based on the position information detected by the mark detecting device.