Disclosed is a fiber coil reel 100 associated with an optical fiber 10 wound therearound to make a predetermined number of turns to be used for an optical fiber gyroscope comprising a fiber coil composed of the lengthy optical fiber 10 to make the predetermined number of turns, a coupler 22 for optically coupling an optical fiber 16 led from a light source to an optical fiber 20 to be led to a photodetector, and an optical IC chip arranged between the fiber coil and the coupler 22 and including a phase modulator and a polarizer mounted on an optical waveguide, wherein a space for winding the lengthy optical fiber 10 around the outer circumference is provided, and a through-hole 102 is provided at the central portion, through which a support shaft 74 of an assembling jig 70 is rotatably inserted. Accordingly, the optical fiber gyroscope can be assembled with ease, and it is possible to effectively reduce the production cost of the optical fiber gyroscope.