The invention discloses a fastener, comprising: (a) a fastening element which has a beam, an engagement device located at one side of the beam, a matrix and a flexible point separated from the beam; and (b) a driving device which is connected to the fastening element and includes a material suitable for contracting in activation. Once the material contacts, the beam is movable between an engagement position and a disengagement position, the matrix has a first arm and a second arm connected by the flexible point, the beam is located at one end of the first arm, and the flexible point and the engagement device are located at the same side as the beam.