A mobile terminal and an interface method thereof for connecting external devices, such as an adapter, a Universal Serial Bus (USB) cable, a docking station, an accessory, and the like, to the mobile terminal are provided. The mobile terminal includes a battery, a connector including a pin for data communication and first and second power pins for charging the battery, a memory for storing a reference voltage indicating a dedicated adapter of the battery, and a controller for receiving a voltage input from the first and second power pins, for recognizing an external device connected with the connector as the dedicated adapter when a voltage input from the pin for data communication is the reference voltage, and for charging the battery with power input to the first and second power pins.