A turbocharging system for use with an internal combustion engine (1), which includes an exhaust gas feeding passage (5) configured to feed exhaust gas of an internal combustion engine (100) toaturbineunit (20); anexhaustgaspassage (6) configured to release the exhaust gas discharged from the turbine unit (20) outside of the turbocharging system; an intake air passage (7) configured to feed intake air into the compressor unit (30); a compressed air passage (33) configured to feed compressed air discharged from the compressor unit (30) to the internal combustion engine (100) ; an intercooler (108) configured to cool the compressed air flowing through the compressed air passage (33); and an LPL-EGR passage (8) configured to recirculate at least a part of the exhaust gas flowing through the exhaust gas passage (6), into the intake air passage (7), wherein the compressed air passage (33) is provided with a cyclone-type collecting device (9) arranged upstream of the intercooler (108) to collect foreign substances contained in the compressed air.