EXHAUST GAS DILUTION DEVICE AND EXHAUST GAS MEASURING SYSTEM USING THE SAME

In order to provide an exhaust gas dilution device 100 capable of making a flow rate range wider than before, the exhaust gas dilution device 100 is adapted to include: a dilution tunnel 2 through which diluent gas such as air flows; an orifice member 51 adapted to block the dilution tunnel 2 except for an orifice hole 5a provided in a central part; and an exhaust gas introduction pipe 1 of which a discharge port 1a is disposed so as to face to the orifice hole 5a and face to a downstream side and through which exhaust gas is discharged from the discharge port 1a into the dilution tunnel 2. In addition, in the exhaust gas dilution device 100, the orifice member 51 is formed with a concave part S that is gradually concaved from an outer circumferential edge part toward the orifice hole 5a as viewed from an upstream side.