PURPOSE: To provide a glass dosimeter whereby stable measured values of dosage can be obtained even if the temperature of the measuring environment varies.

CONSTITUTION: This glass dosimeter, which detects dosed fluorescence using a photomultiplier tube 16 by irradiating a radiation-exposed fluorescent glass 14 with an exciting ultraviolet ray from a laser 11, and detects standard fluorescence using a second photomultiplier tube 18 by irradiating a standard fluorescent glass 15 with part of the exciting ultraviolet ray so as to calculate the dosage of the radiation-exposed fluorescent glass 14 using an arithmetic circuit 25, includes a preamplifier 17 provided at least on the output side of the photomultiplier tube 16 to convert current output into voltage output, having a measurement error compensating means comprising a thermistor 2 with a negative temperature coefficient and a variable resistor 3 to compensate errors in measurements resulting from the difference in temperature characteristic between the photomultiplier tubes 16, 18.