OPTICAL FIBER GIRO

PROBLEM TO BE SOLVED: To provide an optical fiber giro of an easy composition with a high SN ratio. SOLUTION: Since a differential amplifier 20 is adopted as an amplifier to amplify an interference signal from a photoelectric conversion circuit 8 to photo-electrically convert interference light of an optical fiber giro as high as it can be sampled and amplifies two input signals by subtracting the same phase component from each other, a low noise amplification is possible. Further, when one of the two input ports of the differential amplifier 20 is connected with the output port of the photoelectric conversion circuit 8 and the other input port is connected with an earth side of the photoelectric conversion circuit 8, if a same phase component as the noise component in the interference signal output is inputted to the differential amplifier 20 from the photoelectric conversion circuit 8, the same phase components are subtracted to be amplified and the noise component included in the interference signal is eliminated.