A low-loss ferrite comprising as main components 46.5-49.5% by mol of Fe 2 O 3 , 17-26% by mol of ZnO, 4-12% by mol of CuO, and 0.2% or more and less than 1.2% by mol of CoO, the balance being NiO, and 0.03-1.4% by mass (as SnO 2 ) of Sn based on 100% by mass of the main components, and having an average crystal grain size of 0.7-2.5 µm, and an electronic device obtained by integrally sintering pluralities of layers of this low-loss ferrite and coil-shaped electrodes formed in the laminate.