To accurately detect even an object with a depth such as a vehicle body with a simple configuration.

A picked-up image obtained by a camera 1 or the like is processed to extract a 2-dimensional characteristic quantity and it is converted into a 3-dimensional characteristic quantity. The detection accuracy of an object with a depth is improved by providing at least either of calculation sections 18, 19 which calculate an apparent height or width of the object based on the object characteristic quantity or the like including an installation position of the camera or the like and the position and the depth of the object when the 3-dimensional characteristic quantity is compared with a reference object characteristic quantity stored in advance to extract the object.