PURPOSE: To minimize the influence of an ambient condition and to count the number of persons with a high accuracy by detecting the central position of the black circle in the concentration changing direction, detecting the persons and counting the number of persons after the head part of the persons is identified by the concentration characteristic.

CONSTITUTION: When a view illuminated by an infrared ray dropping illuminating means 31 is photographed by a high angle photographing means 32, the image signal is stored into an image memory circuit 34 corresponding to the position. At such a time, the head part image of the person comes to be a black circle. The direction value of respective picture elements of the image is calculated by a concentration changing direction calculating circuit 35 and stored into a concentration changing direction memory circuit 37. A comparing circuit 39, by using the direction value and the address shifting vector of a direction extracting template 38, executes the weighting to respective attention point picture elements, obtains the accumulative value, compares with the set value and obtains the center of the black circle. A concentration comparing circuit 40 reads the concentration value of plural images at the near circumference from the circuit 34, decides the concentration characteristic and at the time of valid, outputs a counting-up signal. A counter 41 outputs the number of the persons in the picture after an address generating circuit 36 scans all picture elements.