To reduce the occupancy space of a wafer treatment device.

A wafer transfer robot suspension, supported to a frame 35 on a ceiling of a wafer treatment device, is used as a wafer transfer mechanism which transfers wafers. The wafer transfer robot comprises a base section 1 suspension supported to the frame 35, a first arm 11 supported by the base section 1 in a turnable state and raising and lowering around a vertical axis, a second arm 12 connected to an end top of the first arm 11 in a state capable of freely turnable around a vertical axis, and a third arm 13 connected to an end top of the second arm 12 in a state of being capable of turning around a vertical axis. The first arm 11, the second arm 12, and the third arm 13 are turned independently by a motor 21, a motor 22, and a motor 23 respectively. The suspension support of the wafer transfer mechanism from the ceiling makes it possible for a space below to be used for the arrangement of the wafer treatment section, its auxiliary facilities, of the like.