The importance of multidisciplinary therapy for intractable malignant tumors is gaining attention, and the opportunities for radiofrequency hyperthermia in patients with metallic implants are also increasing. In this study, we used a tissue-equivalent phantom to examine the influence of the presence of a metal stent on the heating situation. A biliary metallic stent was placed in the center of the tissue-equivalent phantom, and heating was applied using a 25 cm diameter dielectric heating device. The temperature around the stent was measured over time as the angle between the stent and the electrode was changed (0° to 90°). The temperature increased as the angle between the stent and the electrode increased, and when the angle was 30° or more, the temperature at both ends of the stent was significantly higher than the control temperature. Based on our findings, as the angle between the stent and the electrode increases, the effective electric field component along the axial direction of the stent becomes larger, which may result in increased heat generation. It is suggested that radiofrequency hyperthermia in patients with metallic stents may be performed more safely by adjusting the patient’s position on the hyperthermia table when the stent-to-electrode angle is large.