Interleaved boost converter with close-coupled inductor is widely employed in drive system for Hybrid Electric Vehicles (HEV) or in renewable energy system, in order to achieve high power density of the converters. For further high power density of magnetic components, this paper presents calculation method for potential power of the magnetic components in interleaved boost chopper circuit with close-coupled inductor. The calculation method for potential power of magnetic components is based on detailed analysis of the characteristic of inductor current and magnetic flux in the core. By applying the method, more easily, design of magnetic components in high power converters. As a result of analysis of potential power, CRM control scheme is effective for miniaturization of the magnetic components in case of interleaved boost converter with close-coupled inductor. Finally, potential power of the interleaved boost converter with close-coupled inductor is discussed from theoretical and experimental results. In this paper, 'potential power' means allowable power of inductor.