Powder core and high-frequency reactor using the same

A high-frequency reactor comprising a powder core and a winding wound around said powder core, said powder core being obtained by compaction-forming magnetic powder, wherein said magnetic powder is an alloy comprising 1-10 wt % Si, 0.1-1.0 wt % O, and balance Fe, an insulator comprising SiO2 and MgO as main components being interposed between magnetic powder particles, said magnetic powder particles having a particle size of 150 μm or less, and wherein said powder core has an a.c. permeability μ20kHz of 20 or more under an applied d.c. magnetic field of 12000 A/m and a core loss of 1000 kW/m3 or less under the condition of 20 kHz and 0.1 T.