A method of disposing a substrate on a holding unit using a pattern forming apparatus which forms a pattern on the substrate, the pattern forming apparatus comprising: a stage, the holding unit removably attached to the stage and configured to suck and hold the substrate, an optical system, and configured to detect an alignment mark of the substrate from a suction surface side of the substrate, the optical system having plural optical elements, and a detection unit configured to detect a reference mark for measuring a position of a detection field of the optical system, the method comprising: detecting a position of the reference mark, and disposing the substrate on the holding unit using the detected position of the reference mark so that the alignment mark of the substrate detected from the suction surface side of the substrate by the optical system is disposed in the detection field.