A vacuum pump includes a casing provided with an inlet port and an outlet port, a peripheral groove vacuum pump unit disposed in an upper section, with respect to a flow direction of the gas, of the casing, and a vortex vacuum pump unit disposed in a lower section, with respect to the flow direction of the gas, of the casing. The vacuum pump unit and the vortex vacuum pump unit have a common rotor. Since the common rotor is provided for the vacuum pump unit and the vortex vacuum pump unit, the dynamic balance of the rotor can be easily adjusted and the rotor rotates with a minimal amount of vibration.