When products requiring careful handling such as semiconductor wafers and food (hereinafter called “workpieces”) are transported in manufacturing processes, problems can occur due to malfunctions that degrade sanitary conditions during the transport of workpieces through contact. An excellent device for transporting workpieces is a pneumatic non-contact holder (hereinafter called “holder”). However, this device has a disadvantage in that, although the vertical force on the workpiece can be controlled, it is not possible to control the horizontal force. As such, the workpiece is sometimes unstable and slides away from the holder. We changed the shape of the diffuser in the holder, and observed the behavior of the workpiece held by the holder. We measured the holding force and the pressure distribution for several holders in order to determine the influence of the diffuser shape on the behavior of the workpiece.