Certain embodiments provide a high-frequency semiconductor package including: a base which is made of metal and is a grounding portion; a multi-layer wiring resin substrate; a first internal conductor film; and a lid. The multi-layer wiring resin substrate is provided on a top surface of the base, and has a frame shape in which a first cavity from which the top surface of the base is exposed is formed. The first internal conductor film covers surfaces which form a top surface of the multi-layer wiring resin substrate and an inner wall surface of the first cavity, and is electrically connected with the base. The lid is attached onto the multi-layer wiring resin substrate, and seals and covers the first cavity.