A multiband antenna includes a first radiator, a feed element, a first ground element, a second radiator, a connecting element, and a second ground element, wherein the first radiator is made of a metal plate. The feed element is electrically connected to the first radiator and is adapted to feed a signal. The first ground element is electrically connected to the first radiator. The second radiator is made of a metal plate and surrounds an outer side of the first radiator, wherein the first radiator and the second radiator are spaced by an interval. The connecting element is electrically connected to the first radiator and the second radiator. The second ground element is electrically connected to the second radiator. In this way, the multiband antenna is suitable for transmitting signals in multiple frequency bands.