The present invention provides an antenna structure for metal environment. The antenna structure comprises a radiating conductor, a first ground conductor, and a second ground conductor. The radiating conductor comprises a first opening circuit, and a second opening circuit, in which the first opening circuit is opened at a first side of the radiating conductor, and the second opening circuit is opened at a second side of the radiating conductor. The first ground conductor is electrically coupled to a third side of the radiating conductor while the second ground conductor is electrically coupled to a fourth side of the radiating conductor. Alternatively, the present invention further provides an antenna device by folding the antenna structure having RFID chip electrically attached thereon to cover a substrate, whereby the antenna device could be accessed in a metal environment.