The present technology relates to a circuit board, a semiconductor device, and an electronic apparatus that reduce the generation of noise signals. A circuit board includes: a first conductor layer that has a first conductor portion including a conductor having a planar or mesh-like first basic pattern repeatedly disposed in the same plane; and a second conductor layer that has a second conductor portion including a conductor having a planar or mesh-like second basic pattern repeatedly disposed in the same plane, and a third conductor portion including a conductor having a planar, linear, or mesh-shaped third basic pattern repeatedly disposed in the same plane. The repeating cycles of the first and second basic patterns are substantially the same cycles, and the third basic pattern is different than the second basic pattern. The present technology can be applied to a circuit board of a semiconductor device and the like, for example.