A wiring board includes an insulating substrate that is rectangular in a plan view, a plurality of mount electrodes arranged to face each other on a first main surface of the insulating substrate along a pair of opposing sides of the insulating substrate in a plan view, a plurality of terminal electrodes arranged to face each other on a second main surface of the insulating substrate along the pair of opposing sides of the insulating substrate in a perspective plan view, and an inner metal layer arranged inside the insulating substrate and extending in a direction perpendicular to the pair of opposing sides of the insulating substrate in a perspective plan view.