The invention relates to a fastening tool comprising a handheld housing with a piston element (1), which is received in the housing and which can be moved in a driven manner, for transmitting energy to a fixing element (3). The piston element (1) is guided in a cylinder (2) and can be accelerated towards the fixing element (3) by a drive force, and the piston element (1) can be held in a starting position by a magnetic force of a retaining element (5). The retaining element (5) has a first magnetically conductive stop (7) and a second magnetically conductive stop (8). The magnetic stops (7, 8) are connected by a magnetically conductive counter piece (9) arranged on a piston element when the piston element (1) is being held, and excitation magnet (6) is arranged between the magnetically conductive stops (7, 8).