To provide a high convenience vacuum filtration method capable of safely filtering even a solid-liquid mixture containing dangerous materials such as an organic solvent or a reducing catalyst.

This vacuum filtration method includes a process for supplying the solid-liquid mixture on a filter surface 21 of a tray 2, a process for discharging filtrate by reducing the pressure of the underside surface of the filter surface 21 and a process for discharging a solid cake formed on the filter surface 21 by the discharge downward of the filtrate by inclining or overturning the tray 2, and the respective processes are performed in an inert gas filled in a fixed space 10.