PURPOSE: To obtain a miniature digital multi-meter (DMM) which excels in portability, by using a solar battery also for a reflecting plate of an LCD panel of a display body.

CONSTITUTION: A solar battery 10 is set on the rear side of an LCD panel 9. The sun beams 12 entering from the upper part of the panel 9 transmit through two transparent glass plates and reach the battery 10. Some of these beams 12 are absorbed through the battery 10 and converted into electric energy. This electric energy is supplied to each circuit of the DMM. The some rates of the beams 12 are reflected by the battery 10 to raise characters displayed through the panel 9. A liquid crystal contrast circuit 7 controls the liquid crystal of the panel 9 in response to the absorptivity and reflectance of the beams 12. This meter compensates the variance of display contrast of the panel 9 due to the intensity of the beam 12.