A temperature measuring device using an optical fiber Bragg grating sensor is proposed, which includes: an optical fiber wound one or more times on a ring part, which has a preset diameter by rotating a part of the optical fiber once, thereby maintaining a predetermined shape; a housing in which the optical fiber is arranged; and an optical fiber Bragg grating sensor provided in a straight line part of the optical fiber, and thus the present invention prevents deformation of the optical fiber and the optical fiber Bragg grating sensor, which are arranged to be spaced apart at a predetermined distance in the housing, even when deformation occurs in the housing according to a change in the outside temperature, thereby accurately measuring temperature without distortion.