The antenna structure is applied for a communication system. The antenna structure has a signal emitting/receiving portion, a flex transmitting line disposed under the signal emitting/receiving portion and electrically connected to the signal emitting/receiving portion, and a connecting portion having a first end and a second end. The first end of the connecting portion is electrically connected to the flex transmitting line, and the second end of the connecting portion is connected to an assembling portion. The antenna structure further includes a bendable piece corresponding to the flex transmitting line. The bendable piece can be bent by a force to change positions, directions, or positions and directions of the signal emitting/receiving portion connected with the flex transmitting line. The bendable piece, the flex transmitting line and the signal emitting/receiving portion are covered by a sheath.