The vertical treating apparatus according to this invention comprises as major units a process tube for receiving objects to be treated through an opening in a lower part thereof, a lift mechanism (boat elevator) for mounting a wafer boat holding the wafers to load the wafers into the process tube, and a wafer transfer device for transferring the wafers to the lift mechanism. The lift mechanism flexibly supports a cap for closing the opening of the process tube by way of an urging force provided by coil springs, and mounts the wafer boat for holding the wafers on the upper surface thereof. A cap restricting member is provided for restricting the urging force of the coil springs. The cap is provided at a lowermost position of the lift mechanism. Thus, the cap is restricted by the cap restricting member when the wafers are transferred by the transfer device, whereby the wafer boat, etc. are kept from tilting due to flexure of the coil springs, so that particle sticking to the wafers and wafer damage can be avoided.