1. A traffic monitoring device, which comprises: an object information acquiring section including a detection block calculating unit for acquiring, with the use of distance images acquired by imaging an object from above within a supervised sector that is divided into a plurality of blocks, a block having distance measured pixels, obtained by imaging the object from above, as a detection block related to an object present within the supervised sector and operable to acquire a three dimensional object information by the detection block; a block projected image generating unit for generating a block projected image, which is a two dimensional image of a height data of the detection block, by projecting onto a horizontal plane the detection blocks, each having a height data on a two dimensional plane: a template setting unit for setting a template block of a shape related to the object within a block area, the template containing a head, a hairdos buffer and a shoulder rendered to be a template image; a template matching unit for performing a template matching with a block projected image by means of the template block; and a determining unit for determining the number of objects based on the template matching, wherein the template block has the head adjacent to the hairdos buffer and the hairdos buffer adjacent to the shoulder.