To detect the leakage current caused by insulation resistance to the ground.

The leakage current detection device comprises a leakage current detection part for detecting the leakage current from a measuring wireway; an amplifying part for amplifying the converted voltage from the detected leakage current; a first higher harmonic component eliminating part for eliminating the higher harmonic components contained in the voltage amplified in the amplifier part; a voltage-detecting part for detecting the voltage generating in the measuring wireway; a second higher harmonic component eliminating part for eliminating the higher harmonic component contained in the detected voltage; a phase difference detecting part for detecting the phase difference in the two voltages, in which the higher harmonic components are eliminated; a frequency-calculating part for calculating the frequency generated in the measuring wireway, the voltage of which is detected by the voltage detecting part, based on the voltage signal wave form in which the higher harmonic components are eliminated by the second higher harmonic component eliminating part; and a phase angle calculating means for calculating the phase angle of the leakage current flowing in the measuring wireway, based on the phase angle detected by the phase difference detecting part, and the frequency calculated in the frequency calculating part.

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