PURPOSE: To facilitate the high-precision measurement of the end surface angle of an optical fiber, by a method wherein a microscope, equipped with a monocolor light projector a jig which holds the end part of the optical fiber in a manner to enable a light axis to coincide with an optical fiber axis, and a clear parallel plate attached to the jig are mounted.

CONSTITUTION: A measuring device consists of the optical fiber 1, an optical fiber support stand 2, and an abutting plate (clear parallel plate) 3. The side of the optical fiber 1 is positioned along the optical fiber support stand 2, and the end surface of the optical fiber is caused to abut on to the abutting plate 3. The abutting plate 3 is securely attached to the support stand 2 in a manner that its surface is positioned perpendicular to the optical fiber axis. A beat pattern can be obserbed corresponding to the back surface of the abutting plate 3 and the optical fiber end surface by means of B1 and B2, where the B1 is a reflection light at the back surface of the abutting plate 3, and the B2 is a light which the optical fiber end surface reflects and transmits the abutting plate 3. This permits the high-precise and easy measurement of the end surface angle of the optical fiber.