An access protection system for safeguarding an access point to a machine or installation includes a sensor device and an interlocking device. The sensor device includes an optical transmitter and receiver. The interlocking device includes a base body and a blocking element. The optical transmitter is configured to transmit a light pulse to the optical receiver. The sensor device is configured to generate a sensor signal based on reception of the light pulse. The sensor signal is used to control the machine or installation. The blocking element is movable relative to the base body from a release position into a blocking position. The blocking element is configured to be located, while in the blocking position, in a beam path of the light pulse between the optical transmitter and receiver to block the reception of the light pulse. The interlocking device is lockable in the blocking position by a securing element.