A miniaturized multiple input multiple output (MIMO) antenna includes a first antenna element disposed in a first side of a substrate in a round form; a second antenna element in a round form symmetrically with the first antenna element and disposed in the first side of the substrate; and a ground disposed in a second side of the substrate. The first antenna element and the second antenna element are disposed such that electro magnetic waves resonating in the first antenna element and the second antenna element are orthogonally polarized. Accordingly, the antenna size can be reduced. The miniaturized antenna facilitates the component design in the small terminal.