A circuit board including a core layer having a first surface and a second surface opposite to the first surface; a first build-up layer and a second build-up layer formed on the first surface and the second surface of the core layer, respectively, and including a conductive pattern and a conductive via; and an outer layer formed on the surface of the first build-up layer and the second build-up layer, wherein at least one build-up layer of the first build-up layer and the second build-up layer comprises a photosensitive insulating layer in which a cavity is disposed and a thermal dissipation unit disposed in the cavity.