To easily and speedily match an optical axis in a mechanical and optical switch for moving an optical fiber supporting body on a plane for switching.

An optical fiber supporting body 3 is moved in an X-direction within a surface and an optical fiber supporting body 4 is moved in a Y- direction within a surface. A light transmission window 3a having a trapezoidal cross section transmitting light emitted from the fiber 2 is formed at the supporting body 3. In rear of the window 3a, a light detector 6 is arranged. It is supposed that the optical fiber 2 is carried to a position opposing the window 3a by schematic positioning. The supporting body 4 is moved at a fixed speed in a Y direction while emitting laser light from the optical fiber 2. When a time of irradiation with a laser spot by the detector 6 is measured, positional deviation in the X-direction of the optical fiber 1 can be detected and positioning is performed by this. The optical fiber 2 is positioned at the center line position of the window 3a.