A conveyance system that prevents conveyance carriages from mistakenly entering an area includes a rail extending across a plurality of areas, a FOUP conveyance vehicle that travels along the rail, a conveyance vehicle that has a width and a height at least one of which differs from that of the FOUP conveyance vehicle, an optical sensor that is provided to the FOUP conveyance vehicle, arranged at a position that does not overlap the conveyance vehicle in a traveling direction, and detects an obstacle in front, and a member to be detected that is arranged, in an entry section into a certain area where only the conveyance vehicle is allowed to enter, at a position where the conveyance vehicle is allowed to enter the certain area, the position being detectable by the optical sensor provided to the FOUP conveyance vehicle.