An apparatus for transporting envelope blanks in an envelope making machine comprises at least one conveyor belt having a plurality of perforation holes therein, on which envelope blanks are transported through the machine in a conveyor plane. Beneath the conveyor belt is at least one suction chamber by means of which ambient air can be sucked through the perforation holes to retain blanks on the conveyor belt. At least one guide belt is provided on at least one side beside the conveyor belt in the direction of movement thereof. The conveyor belt and the guide belt are drivable so as to move synchronously in the direction of travel of the envelope blanks.