Access protection system for monitoring the access of objects to a monitored area , - having at least one first optoelectronic sensor which is set up to detect an intrusion of an object into the monitored area , - having at least one second optoelectronic sensor (28; 40) which is set up for the spatially resolved monitoring of a prefield located upstream of the monitored area , - and having an evaluation unit which is in signal communication with the first and the second sensor , the evaluation unit being set up to trigger a safety function when an object penetrates the monitored area , and being set up to suppress the safety function when the penetrating object is classified as an approved object , characterized - in that the prefield comprises a plurality of adjacent contour detection fields (36-1, 36-2, 36-3) of the second sensor , - in that the evaluation unit is set up to detect, on the basis of signals which have been received from the second sensor , a contour of an object penetrating into the prefield , in each case within a contour detection field (36-1 or 36-2 or 36-3), and to compare the detected contour with a predetermined reference contour, and to compare the detected position of the detected contour with a reference position of the reference contour in the respective contour detection field (36-1 or 36-2 or 36-3), wherein the reference contour consists of the fact that the contour detection field (36-1 or 36-2 or 36-3) is interrupted on its full width at the reference position, - and the evaluation unit is further arranged to classify the penetrating object as an approved object only if the detected contour corresponds to the reference contour at the reference position. - having at least one first optoelectronic sensor which is set up to detect an intrusion of an object into the monitored area , - having at least one second optoelectronic sensor (28; 40) which is set up for the spatially resolved monitoring of a prefield located upstream of the monitored area , - and having an evaluation unit which is in signal communication with the first and the second sensor , the evaluation unit being set up to trigger a safety function when an object penetrates the monitored area , and being set up to suppress the safety function when the penetrating object is classified as an approved object , - in that the prefield comprises a plurality of adjacent contour detection fields (36-1, 36-2, 36-3) of the second sensor , - in that the evaluation unit is set up to detect, on the basis of signals which have been received from the second sensor , a contour of an object penetrating into the prefield , in each case within a contour detection field (36-1 or 36-2 or 36-3), and to compare the detected contour with a predetermined reference contour, and to compare the detected position of the detected contour with a reference position of the reference contour in the respective contour detection field (36-1 or 36-2 or 36-3), wherein the reference contour consists of the fact that the contour detection field (36-1 or 36-2 or 36-3) is interrupted on its full width at the reference position, - and the evaluation unit is further arranged to classify the penetrating object as an approved object only if the detected contour corresponds to the reference contour at the reference position. <EOS>