A wiring board has a metal-made base having a front surface and a back surface, an insulating frame body bonded to the front surface of the base through a bonding layer made of bonding material, a seating provided in an area that is located at an inner side with respect to the frame body on the front surface of the base, a mounting area where a component is supposed to be mounted on the front surface of the base, and a groove formed on the front surface of the base. The groove is arranged in at least an area between the mounting area and the seating on the front surface in plan view, and extends in a direction crossing an opposing direction of the mounting area and the seating.