PURPOSE: To execute exactly an information transfer by an optical fiber by making a center line of both pieces of a connector coincide with a self-aligning state, when connecting an optical fiber cable.

CONSTITUTION: The end part of an optical fiber is supported by connector pieces 1, 2, respectively, a supporting flange 7 is provided projectingly and annularly on the outside peripheral surface of the connector piece 1, it is supported by a supporting ring 8 consisting of elastic rubber, etc., also a supporting flange 11 is provided projectingly and annularly on the outside peripheral surface of the connector piece 2, and it is installed to a fitting flange 10. As a result, the connector piece 1 is supported by holding the elasticity in the center of a connecting plug 3, and the connector piece 2 is supported in a fixed state in the center of a connecting receptacle 4. The outside peripheral surface of a connecting part 3A formed cylindrically on one end part of the connecting plug 3 is fitted to the inside peripheral surface of a connecting part 4A formed cylindrically on one end part of the connecting receptacle 4, the connector pieces 1, 2 are connected, and the connecting end face of the optical fiber is connected onto the same axial core.