A stage device for holding a substrate in a processing apparatus for processing the substrate includes a stage, a stage rotating mechanism, and a cold heat transfer mechanism. The stage is configured to hold the substrate in a processing chamber. The stage rotating mechanism includes a rotation shaft extending downward from a center of a bottom surface of the stage and a motor configured to rotate the stage via the rotation shaft. The cold heat transfer mechanism includes at least one cold heat transfer body that is fixedly disposed at a position spaced away from the rotation shaft below the stage and is configured to transfer cold heat of a chiller. The cold heat transfer mechanism is disposed with a gap between the cold heat transfer mechanism and the stage.