The present invention provides to a ceramic composition for high-frequency dielectrics which comprises the main ingredients of ZrO.sub.2, SnO.sub.2 and TiO.sub.2 and a subsidiary ingredient of (Mn(NO.sub.3).sub.2.4H.sub.2 O). In accordance with the present invention, a homogeneous ceramic composition can be prepared by a process which comprises the steps of: adding ZrO.sub.2, SnO.sub.2 and TiO.sub.2 by the molar ratio to satisfy (ZrO.sub.2).sub.1-x (SnO.sub.2).sub.x (TiO.sub.2).sub.1+y (wherein, 0.1M<x<0.4M and 0M<y<0.1M); melting and grinding the mixture at 1900.degree. C. or above; and, adding 1% or less of Mn(NO.sub.3).sub.2.4H.sub.2 O by weight of MnO to the mixture. The ceramic composition of the invention has a high dielectric constant of 40 or more, a quality factor of 7000 or more, and a temperature coefficient of resonance frequency below 10. Accordingly, it can be used for an integrated circuit at microwave as well as at high frequency, or for dielectric resonators.