A compact stripline filter for use in a high frequency circuit for a portable telephone, for example, including an internal ground electrode. The filter includes a first resonator having a first main surface, a first ground electrode disposed in an opposed facing relationship to the entire surface of the first main surface of the first resonator, a first dielectric layer interposed between the first main surface of the first resonator and the first ground electrode, and a first internal ground electrode formed in the first dielectric layer and disposed in an opposed facing relationship to a portion of the first main surface of the first resonator.