Abstract: A conventional pilot lamp which is used in a power plant, substation, or other types of plants, each has its own large and heavy weight transformer below the lamp case. In order to obtain a pilot lamp having the same capacity as the conventional pilot lamp even if the transformer is taken away from the lamp case, the pilot lamp of this invention comprises a lamp, a lamp holder, a heat radiating plate fixed within the lamp holder, an extremely small-sized IC type AC-DC constant voltage regulator connected to the input terminal fixed to the lamp holder, and an output terminal connected to the lamp. Thus, the arrangement contemplated produces a pilot lamp having the same capacity as a conventional pilot lamp, without the large and heavy weight of the transformer unit below the lamp case.