A wiring board 10 includes a lower wiring conductor 1, an upper insulating layer 2 laminated on the lower wiring conductor 1 and having a via hole 5 where a bottom surface is the lower wiring conductor 1, and a via conductor 3 connected to the lower wiring conductor 1 and filling the via hole 5; and the upper insulating layer 2 includes a first resin layer 2a and a second resin layer 2b sequentially laminated on the lower wiring conductor 1, the via hole 5 has an annular groove 5a over a whole circumference of the inner wall in a boundary between both resin layers 2a and 2b, and the via conductor 3 fills the groove 5.