In order to reliably separate an unsterilized zone from a sterilized zone in a device for connecting a medical instrument, an adapter component set 28 is for connecting the medical instrument such as an endoscope to an unsterilized device having a timing pulley 27 included in a rotation mechanism for rotating the medical instrument. An adapter 47 holds the medical instrument. A separator 46 has a hollow cylinder shape for inserting the adapter therein. At least the inner surface of the separator is included in the sterilized zone, and the outer surface of the cylinder is connected to the pulley. As connecting parts for connecting a drape for isolating the device having the rotation mechanism from the sterilized zone, a pair of an outlet drape bearing 41 and an outlet drape bearing cover 42 and a pair of an inlet drape bearing 45 and an inlet drape bearing cover 44 are provided.
