The invention relates to a safety switch arrangement (1) for switching the power supply to a working device on and off by means of a sensor signal which is taken to the working device via two evaluation channels (2), each with an actuator (3). The actuators (3) have switch-like means consisting of semiconductor components. Upstream of each actuator (3) there is a computer unit (4) connected to the actuator (3) via two bidirectional leads (5a, 5b, 6a, 6b), whereby readback switching pulses (5a, 5b) are transmitted via the first lead (5a, 5b) from the computer unit (4) to the actuator (3) and readback test pulses are transmitted via the second lead (6a, 6b) from the computer unit (4) to the actuator (3) for functional test purposes. The computer units (4) are connected via a bidirectional lead (5) for their functional testing. In order to test the functions of the actuators (3) the switching statuses of the switch-like means are changed briefly in such a way that the operative condition of the working device is unchanged owing to its inertia. The operating voltages of the computer units (4) are monitored via a voltage monitoring unit (8).