There is provided a fixer for a fiber bragg grating (FBG) sensor, by which the FBG can be installed by any person to provide the FBG sensor with an accurate value, irrespective of a place to be installed, and the FBG sensor can be semi-permanently fixed and protected. The fixer includes a pair of fixing pieces 3 with a bottom surface adhered to the object, in which both ends of the FBG sensor S is inserted and adhered by an adhesive F, a tube 2 for spacing the pair of fixing pieces at regular intervals, in which the FBG sensor S is inserted into a hollow portion of the tube to protect the FBG sensor S from the exterior, and a member for fixing the fixing pieces 3 and the pipe 2, without producing an error of above 0.0002 mm.