To accurately detect air pressure inside a duct even in fire occurrence, and to enhance thereby reliability for control of pressurized air.

This device is provided with pressure sensors 10, 11 for detecting the air pressures in a pressurized air transfer line 2 in respective floors of a building, and a reference pressure detecting tube 15 extended along a vertical direction of the building, and arranged in a portion where opening parts in both upper and lower ends are hardly affected by a fire disaster. The each pressure sensor 10, 11 is constituted to detect the air pressure in the pressurized air transfer line 2 based on a pressure difference with respect to reference pressure, using as the reference pressure the air pressure in the reference pressure detecting tube 15.