A high-frequency circuit element which can be formed by firing simultaneously a microwave magnetic body and a hard magnetic body plate in the form of a laminate. The microwave magnetic body is made of calcium-vadium-iron and the hard magnetic body plate is made of strontium-iron, so that they have approximately the same firing temperature. They are separated by a screening film of palladium or platinum, which prevents the diffusion of strontium ions from the hard magnetic body plate to the microwave magnetic body. This constitution permits the simultaneous firing of the two components. The high-frequency circuit element is useful as a small, high-precision circulator, isolator, or inductor.