This paper deals with the leakage current in an inverter system with a common-mode choke and grounding capacitors. In the conventional common-mode equivalent circuit, the leakage current does not depend on the position of the grounding capacitors. However, the characteristic of the leakage current in connecting the grounding capacitors between the common-mode choke and the rectifier is significantly different from that in connecting the grounding capacitors at the dc-link stage. This paper elucidates the reason why the leakage current in connecting the grounding capacitors at the dc-link stage flows only in the conduction period of the diode rectifier. The new equivalent circuit that reflects this phenomenon is proposed. Moreover, this paper shows the relationship between the positions of grounding capacitors and reduction effects of the leakage current based on a technique that the authors had proposed for an inverter system. The new circuit can also simulate the leakage current in the system using the proposed method.