Temperature dependence of the phase angle of the fluorescence pulse from long afterglow SrAl/sub 2/O/sub 4/:Eu,Dy phosphor sensor materials were measured using the phase angle measurement technique at temperatures between 270 K and 360 K. Phase angle sensitively varies from 180 deg to 100 deg with temperature from 273 K to 360 K. The phase angle measurement technique is potentially useful for the temperature sensing using long afterglow phosphors with extremely high sensitivity.