A guide device for a diffusion vacuum pump having a plurality of annular guide plates. The guide plates being arranged radially, wherein at least one guide plate has a first section starting from a connection point and a second section starting from the connection point. Therein, the first section extends axially in a first direction, the second section extending axially in the opposite second direction. Therein the first section is designed to taper radially and/or the second section is designed to taper radially.