PURPOSE: To obtain the compact optical fiber sensor having the excellent productivity by fitting optical' elements to an optical element insertion part provided at the predetermined position of an optical fiber.

CONSTITUTION: An electric blower heater is used so as to bend an optical fiber along a mold made of stainless steel or ceramics. An optical fiber fixing groove 18 is formed on a board 19 by a rotary blade saw, and an optical fiber element wire 11 is fixed to this board 19. After fixing the optical fiber on the board 19, an optical element insertion groove 17, into which an optical element such as a polarizer, an analyzer, and a magnetic optical material is to be inserted. A polarizer 13 made of glass polarizing plate, an analyzer 15 and a garnet crystal 14 are inserted into the formed groove 17, and lastly they are fixed by the resin adhesive agent. At this stage, thickness of each optical element is formed at 0.55mm, and the polarizing surfaces of the polarizer 13 and the analyzer 15 are set at 45 degree.