There is provided a thermoluminescent phosphor characterized in that a distribution of the emission intensity of thermoluminescence is present in a visible range that does not overlap the peak of the heating-caused emission intensity of the thermoluminescent phosphor itself and also has one peak within a temperature range in which a resin to be used as a binder can resist heat optically. There is also provided a method of producing the thermoluminescent phosphor. More specifically, there are provided a thermoluminescent phosphor that comprises lithium heptaborate as a base material and copper as a luminescent center present in the base material and which is characterized in that the distribution of the emission intensity of thermoluminescence versus temperature is a sole and monomodal distribution within the range of from 45° C. to 130° C., and a method of producing the thermoluminescent phosphor.

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