A Multiple-Input and Multiple-Output (MIMO) antenna having a plurality of isolation adjustment portions is provided. The MIMO antenna includes a plurality of radiation elements and a plurality of isolation adjustment portions. The plurality of radiation elements is symmetrically formed on the surfaces of the left and right sides of a dielectric element having a predetermined shape, is spaced apart from each other by a predetermined distance, operates in multiple frequency bands, and includes feeding portions, respectively. The plurality of isolation adjustment portions is coupled to the plurality of radiation elements so that they have electromagnetic characteristics different from those of the plurality of radiation elements, thereby improving isolation in each of the frequency bands in which the plurality of radiation elements operate.