<p>A system for removing harm of a large capacity of exhaust gas surely in safety while simplifying management of operation and exhibiting excellent maintainability. The system (10) for removing harm of exhaust gas comprises main piping (12) for collecting exhaust gas (E) discharged from a semiconductor production apparatus, a plurality of units (16) connected with the main piping (12) through individual inlet piping (14) in the inside and removing harm of exhaust gas (E) supplied via the individual inlet piping (14), and an exhaust duct (20) connected with each unit (16) through individual outlet piping (18) to which an exhaust fan (40) is fixed and discharging the exhaust gas (E) processed through each unit (16) while collecting into the atmosphere wherein an inlet pressure sensor (24) for measuring the pressure in each individual inlet piping (14) is fixed and a controller (22) controls the number of revolutions of each exhaust fan (40) such that the pressure measured by each inlet pressure sensor (24) becomes constant.</p>
