An electronic component housing unit includes: a substrate including a mounting region on which an electronic component is mounted; a connection conductor extending from a top face to a bottom face of the substrate, the connection conductor being electrically connected to the electronic component; a wiring conductor disposed on the bottom face of the substrate, one end of the wiring conductor being electrically connected to the connection conductor, another end of the wiring conductor being drawn out from a side face of the substrate; and a ground conductor disposed on the bottom face of the substrate, the ground conductor forming a coplanar line along with the wiring conductor. A bottom face of the wiring conductor is located above a bottom face of the ground conductor.