A high-frequency communication device includes a transmitting and receiving circuit board on which a transmitting and receiving circuit that processes a quasi-millimeter-wave and millimeter-wave signal is mounted, and a shield case attached to cover the transmitting and receiving circuit on the transmitting and receiving circuit board. Protrusions and a radio wave absorption sheet are disposed on an inner surface of the shield case opposing the transmitting and receiving circuit board, the protrusions being regularly arranged. The radio wave absorption sheet is disposed in at least one area of the shield case opposing an active component of the transmitting and receiving circuit, the protrusions being disposed in at least one area of the shield case that opposes one of a passive component and a circuit pattern section of the transmitting and receiving circuit. A thickness of the radio wave absorption sheet is smaller than a height of the protrusion.