A gas friction pump, comprising stationary pump-active components (14) and rotatable pump-active components (15) secured on a rotatable rotor shaft (4), wherein the rotor shaft is supported with a bearing (5) at the high-vacuum-side end and a bearing arrangement at a fore-vacuum side end, characterized in that the high-vacuum side bearing is formed as a conventional bearing, and the fore-vacuum bearing arrangement contains at least one gas bearing. In an advantageous embodiment, the gas bearing is formed as a module and can be brought in engagement with a cylindrical portion of the housing and secured therein.