A transcutaneous energy transmission system (TETS) that supplies power to ventricular assist devices has been studied. TETS causes conducted emissions (CE) and radiated emissions because it transmits large electromagnetic energy(approximately 15 W). In this study, the CE from TETS was measured and the reduction method of CE was investigated. First, the optimum phase shift time between the drain-source voltage and the drain current of the MOSFET in the inverter circuit of TETS was determined by adjusting the resonance capacitor C₁. Second, the parasitic capacitance between the primary and secondary coils of the high-frequency isolation transformer was reduced by changing the winding pattern. As a result, the CE was reduced by 80 dBµV at 5 MHz by insertion of C₁ of 7.74 nF. Additionally, by using an isolation transformer with concentrated winding, the CE was reduced by 9 dBµV at 15 MHz, as compared to the isolation transformer with uniform winding.