<p>An abnormality detecting device comprises a color indication material (4) fixed in an insulating medium, a light source (6) for emitting light which has a wavelength band region which changes due to the color reaction of the color indication material (4), a spectral decomposing device (7) for decomposing light which is reflected by or transmitted through the color indication material (4) from the light source (6) or which is synthesized with the reflected or transmitted light, a sensor (8) for detecting the light which has been subjected to spectral decomposition, and an operating means (9) which operates the output of the sensor (8) to thereby output a signal corresponding to the intensity of the light having a specified wavelength.</p>
