GROUNDING RESISTANCE METER

PROBLEM TO BE SOLVED: To obtain a grounding resistance meter in which open-circuit voltages can be changed over properly even under various measuring conditions. SOLUTION: In this grounding resistance meter by an AC potential difference system, the grounding resistance of a grounding electrode is measured on the basis of a measuring current which flows to the grounding electrode at a time when a first auxiliary electrode and a second auxiliary electrode which are installed sequentially at a ground with reference to the grounding electrode are used and at a time when a measuring voltage is applied across the grounding electrode and the second auxiliary electrode and on the basis of a voltage which is generated in the first auxiliary electrode. The grounding resistance meter is provided with an oscillation circuit 51 which oscillates a set voltage. In addition, it is provided with a transformer 52 in which an oscillation voltage from the oscillation circuit 51 is applied to the primary side and in which the oscillation voltage on the primary side is converted into a plurality of voltages at different levels so as to be output from the secondary side. In addition, it is provided with a changeover switching circuit 53 in which the output voltages from the secondary side of the transformer 52 are changed over sequentially so as to be output as the measuring voltage.