In holding a substrate p loaded at a specified position on a holder 30 by clamping a peripheral region of the substrate p against the holder 30 through a plurality of engagement elements 32, it can be avoided that when the substrate p is offset from the specified position and its peripheral region gets on one or some of the engagement elements 32, the substrate p is processed with the peripheral region getting on the engagement element 32. A substrate holding device includes: a plurality of detector sensors 80 for detecting the peripheral region of the substrate p if the substrate p is placed at the specified position on the holder 30; and a determination unit 90 for determining that the substrate p is offset from the specified position when at least one of the detector sensors 80 did not detect the associated part of the substrate p.