To provide an aligner for suppressing the change of a wavefront aberration generated in the measurement system of a Fizeau interferometer and preventing the deterioration of measurement accuracy of the wavefront aberration of a projection optical system.

The aligner comprises: the Fizeau interferometer comprising an objective lens front group loaded on an original stage and provided with a Fizeau surface for forming reference light, an objective lens rear group positioned more on the upstream side than the objective lens front group, and a reflection mirror loaded on a substrate stage for forming light to be detected; and a TTR type detection system provided with a third objective lens group positioned more on the upstream side than the mark of an original reference plate, for simultaneously observing the mark of the original reference plate configured on the original stage and the mark of a substrate reference plate configured on the substrate stage through a projection optical system and measuring the relative position of the original stage and the substrate stage. In the aligner for projecting and aligning the pattern of the original on a substrate through the projection optical system, the objective lens rear group and the third objective lens group are arranged at the same driving table configured separately from the original stage.