An electromagnetic bandgap structure and a printed circuit board that can solve a mixed signal problem between an analog circuit and a digital circuit are disclosed. In accordance with an embodiment of the present invention, the electromagnetic bandgap structure can include a metal layer; and a plurality of mushroom type structures including a metal plate and a via. Here, the plurality of mushroom type structures can be formed on the metal layer in a stacked structure. With the present invention, the small sized electromagnetic bandgap structure can have a lower bandgap frequency.