Disclosed is an exhaust system for discharging a fluid which is supplied into a hermetically closed container 54 for containing a semiconductor wafer W, a substrate to be supplied in the container 54 and subjected to a process. The exhaust system comprises an outer exhaust pipe 71 which is connected to the hermetically closed container via an exhaust connecting pipe 68 and has closed top and bottom ends, a downstream guide passage 201 which is provided in the outer exhaust pipe 71 and adapted to downwardly guide an exhaust fluid flowing through the outer exhaust pipe 71, and an upstream guide passage 202 which is adapted to upwardly guide the exhaust fluid having flowed through the downstream guide passage 201 as well as to cause foreign matter or the like in the exhaust fluid to be settled by gravity. The exhaust fluid having flowed through the upstream guide passage 202 is discharged from a discharging passage 203 to the outside.