A class of LC resonators for micromagnetic sensor devices is reported, which is fabricated by means of the microelectromechanical system (MEMS) technique. The micro-LC resonator consists of a solenoidal microinductor with a bundle of soft magnetic microwire cores and a capacitor connected in parallel to the microinductor. The core magnetic material is a tiny glass-coated Co83.2B3.3Si5.9Mn7.6 microwire fabricated by a glass-coated melt-spinning technique. The solenoidal microinductors fabricated by the MEMS technique were 500–1000 μm in length with 10–20 turns. The changes of inductance as a function of external magnetic field in microinductors with appropriately annealed microwire cores were varied as much as 370%. Because the permeability of ultrasoft magnetic microwire is changing rapidly as a function of external magnetic field, the inductance ratio as well as magnetoimpedance ratio (MIR) in a LC resonator is varied accordingly as a function of external magnetic field. The MIR curves can be tuned very precisely to obtain maximum sensitivity.