A variable-frequency LC filter that has sharp attenuation characteristics and that does not increase the size of a substrate and a high-frequency frontend module using such a variable-frequency LC filter are provided. A first variable capacitor and a second variable capacitor are disposed on a principal surface such that strength of magnetic field coupling caused between a first inductor and a third inductor is greater than strength of magnetic field coupling caused between a second inductor and the first inductor and than strength of magnetic field coupling caused between the second inductor and the third inductor.