To provide a processing device capable of surely holding a substrate in a state where the substrate is not rotated or rotated at low speeds.

A cleaning unit(CLU) 21a of one embodiment of the processing device has a freely rotating spin plate 26 on which a holding member 25a for nearly horizontally holding a wafer W is mounted. The holding member 25a has a support 33, a moving pin 62 having a holding portion 62b for holding the wafer W, and a weight body 63 having a weight 63b. The moving pin 62 turns such that when the wafer W is placed on the holding portion 62b, a pressure for holding the wafer W is applied to the wafer W by the own weight W. Moreover, when the spin plate 26 is rotated, the weight 63b is moved outside by a centrifugal force to abut against the moving pin 62 to increase the pressure by which the holding portion 62b holds the wafer W.