A device for enhancing induced magnetic field consequent for thermal ablation therapy includes a magnetic field generating unit, an annular support and a magnetic ring. The annular support is non-magnetic and non-electrically-conductive, and has two annular end faces and annular outer and inner walls. The magnetic field generating unit is fixed around and contacts the annular outer wall. The magnetic ring is magnetic, has a ring body confining a ring opening, fixed to one of the annular inner wall and the annular end faces, and extending around a common axial line that extends through the annular inner wall. The ring opening is smaller than the annular inner wall in dimension on a plane perpendicular to the common axial line.
