Disclosed is a multi-band antenna unit of a mobile terminal that includes an antenna, switch, sensor, first matching circuit, second matching circuit, diplexer, first signal processing unit, and second signal processing unit. The antenna is movably installed between first and second contacts, and transmits and receives first and second signals of different frequency bands. The switch connects the first contact to the first matching circuit or the second contact through the second matching circuit. The sensor detects an antenna position, and allowing selective connection of first or second matching circuits. Transmission and reception of multiple signals of various frequency bands is enabled using a single antenna unit, reducing the number of components, cost, and size of a mobile terminal. Additionally, performance of an antenna is improved by connecting to a proper matching circuit according to the position of the antenna.