In a device for supplying a printing substrate web to an internal transport path of the printing substrate web of a printing device, a device accepts the printing substrate web from the printing substrate web source. A drive unit is provided at an output of the device and draws the printing substrate web from the device. A buffer device having a buffer reservoir is provided at an output of the drive unit. The buffer reservoir has a negative pressure device that generates a negative pressure in a buffer reservoir. The negative pressure acts on the printing substrate web to pull the printing substrate web drawn by the drive unit into the buffer reservoir and thereby tensions the printing substrate web before it is supplied to the internal transport path.