The present invention provides a lithography apparatus including a sensor configured to detect each of an image of a first mark on a first surface of a substrate and a second mark on a second surface opposite to the first surface, and a processor configured to perform processing of deciding a measurement focus position at which the sensor can detect both the image of the first mark and the image of the second mark based on first mark detection information obtained in a focus state of the optical system in which the sensor can detect the image of the first mark, and second mark detection information obtained in a focus state in which the sensor can detect the image of the second mark.