PURPOSE: To improve the sensitivity to radiation, the linearity of the absorption quantity, the fading property, etc. by adding specific amounts of oxides, which are calculated in terms of CoO, CuO, and Cr2O3, to a glass for a fiber type dosimeter.

CONSTITUTION: A fiber having 50W200μ diameter is formed with the glass where 0.1W10ppm CoO, 10W100ppm CuO, and 2W100ppm Cr2O3 are added to a borosilicate glass or a silicate glass. This fiber 2 is spiraled, and a light emitting diode 1 and a detecting element (photo diode) 3 are connected to both terminals, and an operating circuit which converts attenuation of light transmission colored by irradiation of radiation to a dose of radiation and a display device where the dose of radiation is displayed are provided. CoO stabilizes the center of coloring to prevent fading, and CuO promotes coloring, and Cr2O3 has an effect to cut ultraviolet rays. Thus, the glass is obtained which has a maximum transmitted light coinciding with 500W650nm center wavelength of light emission of the light emitting diode (GaP or the like), a high sensitivity, and a linearity with respect to a wide-range radiation dose.