Abstract: A system for counting living beings moving on a first surface (0) and passing through a second cylindrical surface with substantially vertical generatrix, consists of N thermal radiating detection cells (11) having in particular a thermopile (30) including at least a sensitive element (31), and elements focusing (34) the thermal radiation and generating a field of vision (111) extended along a direction, the N detection cells (11) being distributed between two curves, one of the curves coinciding with the base line of the cylindrical surface crossed by the living beings, and the other curve being distant from the former one by a length D (42) equal to 5 cm at least, the direction of the extension of the field of vision of each cell being substantially tangent to one of the two curves.