PURPOSE: To detect only a part having height since the part is projected at a different position in a converted image by projecting and converting an image of one camera into an image of the other camera on the basis of specific coordinates.

CONSTITUTION: Image signals picked up downward by the 1st television camera 11 and 2nd television camera 12 are inputted to an A/D conversion part 13 and converted into digital signals, which are stored in a 1st multi-valued image memory part 15 and a 2nd multi-valued image memory 16. A stationary body detection area setting part 14 previously set which area of the 1st multi-valued image memory part 15 and 2nd multi-valued image memory part 16 a stationary body is decided. A correspondence coordinate setting part 18 sets which position of a plane part in an image in the multi-valued image memory part 15 and multi-valued image memory part 16 is made to correspond. A projection conversion part 17 performs a projection converting process for the image in the multi-valued image memory part 15 by a conversion expression found from correspondence coordinates set by a correspondence coordinate setting part 18.