Abstract: The disclosure relates to sheet separating device for a stack counting apparatus including a counting head to traverse a corner of a stack and having a horizontal suction blade with a suction orifice on its upper surface for insertion in the stack and oscillatable about a horizontal axis to separate a corner of a sheet in the stack adhered by the suction port to the blade from the next sheet. A wiping pin is driven in an elongate orbit around the blade from the trailing edge thereof over the upper surface to the leading edge and along the underside of the blade to transfer a corner of a sheet adhered to the upper surface of the blade from the upper surface to the lower surface. A counting device is arranged to count the number of sheets transferred by the pin.