A technical problem to be solved by the present invention is to provide a mounting device capable of smoothly mounting a drive unit being in a hanging state to a sliding nozzle device, using a manipulator. The present invention provides a mounting device 4 mounted to a distal end of a manipulator 4 to mount a drive unit 31b whose upper end is connected to a suspending device, to a holder 36 of a sliding nozzle device 3. The mounting device 5 comprises: a holding part 52 for holding an upper portion or central portion (to-be-held plate 313) of the drive unit 31b; and a contact part 55c which is contactable with a lower portion (to-be-contacted part 314) of the drive unit 31b when mounting the drive unit 31b to the holder.