A distributed fiber optic sensor device that employs a photonic band gap fiber as a sensing medium, in which: the photonic band gap fiber, which is the sensing medium, includes: a quartz section; and a plurality of high refractive index portions provided in the quartz section along the longitudinal direction of the fiber, the high refractive index portions being photonic band gaps periodically arranged to form a triangular-lattice pattern; the photonic band gap fiber has a bandwidth in which a wavelength band of a Stokes beam generated due to stimulated Raman scattering is included; and the photonic band gap fiber has a band gap width in which a wavelength band of an anti-Stokes beam generated due to the stimulated Raman scattering and a wavelength band of an optical signal incident into the photonic band gap fiber are included.