Abstract: For the very accurate measurement of fluid, particularly gas or hydraulic fluid, pressures, the device comprises a vertical cylinder, a piston adapted to slide in this cylinder with viscous friction, the pressure to be measured being applied to the upper face of the piston, means (motor) for rotating said piston in said cylinder, an electromagnetic precision weighing machine with a display comprising a shaft to which is applied the force to be measured, and means for transmitting to said shaft the force applied to the piston by the pressure to be measured, with limitation of the maximum forces.