The effects of an amphiphilic agent and the orientation of BN on the microwave dielectric properties of BN / polyvinyl butyral (PVB) composites were investigated as a function of the BN content in volume fractions from 0.1 to 0.5 ($V_f$). The plate-shaped BN samples were oriented in the PVB matrix by physical processes, in this case tape casting and laminate methods. With an increase in the BN content, the dielectric constant (K) increased because the K of BN was higher than that of the PVB. At the same BN content, composites with an in-plane orientation of the BN showed a higher dielectric constant than that of composites with a transverse orientation of the BN because the ceramics were oriented parallel to the electric field. All of the composites showed nearly constant K values ranging from 1 to 9.4 GHz, indicating good frequency stability over a wide frequency range. At the same frequency, the K values of the composites increased with an increase in the BN content.