A printed wiring board includes a main wiring board having a main wiring pattern, and a sub wiring board mounted to the main board and having a sub wiring pattern such that the sub pattern electrically connects first and second electronic components, first conductor pads positioned to connect the first component to the main board and the sub board and having surfaces such that the first component is mounted onto the surfaces of the first pads via solder bumps, and second conductor pads positioned to connect the second component to the main board and the sub board and having surfaces such that the second component is mounted onto the surfaces of the second pads via solder bumps. The first and second pads are formed such that the surfaces of the first and second pads are formed on the same plane and have the same shape and the same size.