A semiconductor device 1 is a semiconductor device of the BGA type, and includes a semiconductor chip 10, a resin layer 20, an insulating layer 30, and an external electrode pad 40. The resin layer 20 is constituted by a sealing resin 22 and an underfill resin 24, and covers the semiconductor chip 10. The insulating layer 30 is formed on the resin layer 20. The external electrode pad 40 is formed in the insulating layer 30. This external electrode pad 40 extends through the insulating layer 30. One surface S1 of the external electrode pad 40 is exposed in the surface of the insulating layer 30, and the other surface S2 is located in the resin layer 20. A concave portion 45 is formed in the surface S2 of the external electrode pad 40. The resin composing the resin layer 20 enters into the concave portion 45.