A mounting substrate includes a resin layer and a first conductor including a contact surface in contact with the resin layer. The first conductor includes a first surface facing toward the mounting surface and a second surface on a side opposite to the first surface and extends in a direction parallel or substantially parallel to the mounting surface. The first conductor has a difference of a maximum value and a minimum value of a distance between the first surface and the mounting surface smaller than a difference of a maximum value and a minimum value of a distance between the second surface and the mounting surface. The resin layer includes a resin wall portion surrounding an opening portion partially exposing the first conductor on the mounting surface side, and the first conductor includes an exposed portion defining a mounting electrode.