PURPOSE: To measure pressure consistently from atmospheric pressure to superhigh vacuum area with a small single type apparatus, by carrying a mechanical vibrator type manometer and an ionization type manometer on a single flange while a control circuit is provided to operate the former in a low vacuum area and the latter in a high vacuum area.

CONSTITUTION: An ionization type manometer 1 capable of measuring a pressure area of high vacuum and a mechanical vibration type manometer 2 capable of measuring a pressure area from atmospheric pressure to low vacuum are carried on a flange 3 in common. The flange 3 is abutted against an opening of a vacuum chamber through an O ring 4 and fixed tightly with a bolt into a screw hole 5. To drive the gas manometers, a control circuit 6 is provided. The ionization type manometer 1 is operated by a control signal with the detection that the pressure value measured with the mechanical vibrator type manometer 2 falls below a specified value. This enables the measurement of pressure consistently from atmospheric pressure to superhigh vacuum with a small single type apparatus.