This paper introduces a novel tunable inductor whose inductance can be adjusted continuously in a large range. The new inductor has one winding wrapped on a magnetic flux valve (MFV) and two C-cores attached to each side of the MFV to form a closed magnetic circuit. Its inductance can be altered continuously by applying an external control voltage on the MFV. This paper presents the concept, configuration, and working principle of the proposed novel tunable inductor. The calculation of the inductance is also introduced based the equivalent magnetic circuit theory. A prototype of the tunable inductor is designed and constructed. Experiments are performed on the prototype to prove the proposed tunable inductor concept.