The invention provides a composite dielectric filter device that can easily improve the isolation characteristics between mutually adjacent filters, even when using a compact dielectric block to miniaturize the entire configuration of the device. The invention also provides a communication apparatus incorporating the filter device. In the filter device, inner conductor holes are arranged inside a single dielectric block, and an outer conductor is formed on outer faces of the dielectric block. Additionally, an outer-conductor-free portion is formed at the boundary between a transmission filter and a reception filter formed by the inner conductor holes.