RESISTANCE MEASURING DEVICE

PROBLEM TO BE SOLVED: To avoid an error of a resistance value by notifying the influence of noise.SOLUTION: The resistance measuring device includes: a voltage injection unit 41 for injecting an inspection AC signal Vx; a current detection unit 42 for detecting AC current Ix flowing in a measurement target circuit 5 by use of a second coil 23 and performing synchronous detection with a reference signal Sr, thereby outputting a difference signal Vf of an amplitude corresponding to the amplitude of the AC current Ix; a processing unit 44 for calculating a resistance value Rx based on the current value of the AC current Ix calculated based on the difference signal Vf and the voltage value of the inspection AC signal Vx; a detecting unit 72 for comparing the signal waveform of a positive-polarity signal Vd, which is a single-polarity signal, with a threshold value voltage Vth defined in a reverse, negative-polarity area, and outputting a pulse signal Sp when this signal waveform is beyond the threshold value voltage Vth; and an output unit 45. Based on an average voltage Vave of a pulse signal Sp, the processing unit 44 determines whether the AC current Ix contains noise component or not. If the AC current Ix contains a noise component, the processing unit 44 causes the output unit 45 to output the information about it.