Abstract: An internal combustion-engined setting tool includes a drive piston (15) displaceably supported in the piston guide (17) and displaceable in a setting direction (4) by expandable gases produced in the main combustion chamber (11) of the tool and pre-chamber (20) for generating pressure that is transmitted to the main combustion chamber (11) before the ignition (19) of the air-fuel mixture in the main combustion chamber takes place, with the pre-chamber (20) being formed by space a within the piston guide (17) beneath a bottom of the drive piston (15) remote from the main combustion chamber (11), when the drive piston occupies its initial position, and with the pre-chamber (20) being connected with the main combustion chamber (11) by a transfer guide.