PURPOSE: To improve the efficiency of scraping and conveyance when sludge in a filtering pond is scraped and to reliably scrape a filtering pond surface layer by keeping a weight balance.

CONSTITUTION: A sampling device 12 is elevatably attached to the front of a self-running type machine body 1 and the sampling device 12 is provided with a sludge scraping bottom plate 47, a sand collecting device 9 at the inside, and a sand pumping-up device 14 to convey collected sludge in a tank 7. A pumping-up cylinder 19 and a sand discharging cylinder 22 are rockably installed at the rear central part of the tank 7, and sludge stored in the tank 7 is discharged to the outside.