An apparatus (1) for sterilizing containers (10), comprising a treatment head (5) which has an exit window (8) through which charge carriers can pass, comprising a charge carrier generation source which generates charge carriers, and comprising an acceleration device (6) which accelerates the charge carriers in the direction of the exit window (8). According to the invention, the cross section of the treatment head (5) is dimensioned such that the treatment head (5) can be guided through the mouth of the container (10), and the acceleration device (6) accelerates the charge carriers in such a way that the charge carriers exiting from the exit window (8) can be aimed preferably directly onto an inner wall (15) of the container (10).