To provide a multistage vacuum pump device having greatly reduced power consumption under the condition that a degree of vacuum is relatively high.

The multistage vacuum pump device has a main suction port and a main discharge port spatially communicated with each other via a plurality of pumps arranged in series to one another. Herein, the plurality of pumps are divided into an upstream side pump group and a downstream side pump group so that only the downstream side pump group can be driven. During low load (high vacuum), only the downstream side pump group is driven to pump fluid.