A Multiple Input Multiple Output (MIMO) antenna apparatus is provided. The apparatus includes antenna devices that operate in respective resonant frequency bands. The apparatus also includes a main board comprising a device region and a ground region. The antenna devices are disposed on the device region. The ground plate is disposed on the ground region for grounding the antenna devices. The apparatus also includes at least one isolation device having a negatively charged line that protrudes from the ground plate and extends between the antenna devices on the device region, and a positively charged line that extends around the negatively charged line and connects the antenna devices to each other. The isolation device induces an electromagnetic wave that is generated by the antenna devices between the negative and positively charged lines to isolate the antenna devices from each other.