PURPOSE: To obtain the monitor system able to recognize a person or a kind of an animal invaded in a monitor area by detecting a height and width and a rhythm of walking of a person or an animal with a TV camera or an infrared ray camera.

CONSTITUTION: An image pickup device 101 using a black/white TV camera or an infrared ray TV camera is mounted to a turning base 102 and installed toward a monitor area. A picture processing unit binarizes an inter-frame difference picture in the case of a black/white TV picture, and '1' is set to pixels of a threshold level or over and '0' is set to pixels less than the threshold temperature level in the difference. In the case of an infrared ray picture, '1' is set to pixels of a threshold level or over and '0' is set to pixels less than the threshold temperature level in the difference and the area whose pixels are set to '1' is selected to be a moving body area. Then the moving body area is traced to decide whether a moving body is a person or an animal based on the height, the width, the area and the walking rhythm, its kind, position and speed are outputted from an alarm output section. Through the constitution above, a person or an animal is distinguished from a moving vehicle such as an automobile and a tree rustling in the wind and whether the moving object is a person or an animal is recognized.