Wiring board, semiconductor device, and method for manufacturing wiring board

A wiring board, comprising:

• a first insulating layer containing a thermosetting resin;
• a first wiring layer stacked on an upper surface of the first insulating layer;
• a second insulating layer stacked on the upper surface of the first insulating layer, the second insulating layer containing a first photosensitive resin;
• a second wiring layer stacked on an upper surface of the second insulating layer, the second wiring layer electrically connecting to the first wiring layer;
• and
• a third insulating layer stacked on the upper surface of the second insulating layer, the third insulating layer containing the first photosensitive resin, wherein
• an outer side surface of the second insulating layer is flush with an outer side surface of the first insulating layer,
• an outer side surface of the third insulating layer is located inside the outer side surface of the second insulating layer in a plan view, and
• the upper surface of the second insulating layer connecting to the outer side surface of the second insulating layer is exposed from the third insulating layer.