We investigate lateral manipulation of single adatoms on Si(111)-(7×7) surface using non-contact atomic force microscopy at room temperature. An atomic vacancy is used as an open space for the lateral manipulation. The tip trajectory signal of line scans during the manipulation can be successfully detected and clarifies the presence of quasi-stable adsorption sites on the surface. We also show that the mechanism of the manipulation is attributed to the short-range attractive interaction force from the tip apex atoms.