A conveying apparatus for conveying sheets to a printing press includes at least one suction belt movable over a table; at least one suction chamber disposed below the table for sucking air through the at least one suction belt, so that the sheets are sucked on the at least one suction belt and guided along the table to the printing press; a pressure reducing means for reducing air pressure within said at least one suction chamber; and an air pressure controlling means for controlling said pressure reducing means according to the information regarding the sheets inputted to said air pressure controlling means, thereby adjusting the reduction in the air pressure within the at least one suction chamber.