PURPOSE: To exactly execute the density sampling of an original by detecting the center position of a table, in a table moving type copying machine.

CONSTITUTION: The center position before starting the sampling of a table 10 is detected by a center detecting switch SW3 which is provided on a machine body 20 of a copying machine, and a center detecting path 15 of a moving table 10. From such a position, the table 10 starts its movement, and even against different originals of various sizes, the whitest part of the original is detected and stored before starting a copying operation, therefore, the density sampling of the original is executed exactly.