PROBLEM TO BE SOLVED: To provide techniques reducing loads applied to a catheter and an MDU (Motor Drive Unit) and further enabling a long-term use of the MDU in a simple configuration.SOLUTION: A catheter connector includes, in the inside thereof, a knob comprising a rotatable cylindrical part that holds an optical fiber, with the end face of the optical fiber exposed, and a flange part, the movement range of which is regulated in the axial direction of the cylindrical part. Consequently, even when the cylindrical part is retreated by receiving push-in force for connecting the catheter to the MDU, and the flange part comes into contact with an elastic body, this configuration can retain such a relationship that the cylindrical part is rotatable with respect to the flange part.
