A printing machine for printing on planar substrates, in particular circuit boards. The printing machine includes a printing table which extends in a horizontal plane and on which at least one substrate to be printed on can be arranged and at least one printing device assigned to the printing table. The printing device has a screen holder for an interchangeable printing screen and a doctor device assigned to the screen holder, wherein, by means of the doctor device, a printing material can be applied onto the substrate to be printed on through the printing screen. A screen magazine is assigned to the doctor device for storing at least one printing screen for the doctor device.