Wiring board and method for producing wiring board

This wiring board 1 is provided with: a supporting body 10 which has a plurality of openings 13 that penetrate therethrough from an upper surface 101 to a lower surface 102; and a conductor 20 that issupported by the supporting body 10. The conductor 20 comprises: a first outer layer 21 that is formed on the upper surface 101 of the supporting body 10; a second outer layer 22 that is formed on the lower surface 102 of the supporting body 10 and has a shape that is substantially same as the shape of the first outer layer 21; and an inner layer 23 that is formed within the supporting body 10 and connects the first outer layer 21 and the second outer layer 22 to each other. The inner layer 23 has a frame shape that extends along the outer periphery of the first outer layer, while extending along the second outer layer 22. 布线基板(1)具备：支承体(10)，其具有从上表面(101)贯通至下表面(102)的多个开口(13)；以及导电体(20)，其被支承体(10)支承，导电体(20)包括：第外侧层(21)，其形成于支承体(10)的上表面(101)；第二外侧层(22)，其形成于支承体(10)的下表面(102)，并具有与第外侧层(21)实质上相同的形状；以及内侧层(23)，其形成于支承体(10)内，连接第外侧