A substrate holding apparatus includes a rotary table rotatable about a vertical center axis for supporting a substrate in a horizontal plane, and substrate travel regulating pins fixed to the rotary table and arranged at positions in contact with the outer edge of the substrate so that the center of gravity of the substrate supported on the rotary table is spaced from the center axis for regulating the travel of the substrate in a horizontal direction. Centrifugal force generated with respect to the substrate when the rotary table rotates about the center axis, urges the periphery of the substrate towards the travel regulating pins so that the resulting frictional force prevents rotary slippage between the substrate and the rotary table as rotation of the latter relates to the latter. The structure of this apparatus is simple because the substrate holding portion does not include a movable portion. It is easy to mount a substrate onto this apparatus because it is not necessary to align the orientation flat and the like at a predetermined position.