CARRIER SYSTEM

PROBLEM TO BE SOLVED: To provide a carrier system for efficiently carrying sheets for conveyance in a process. SOLUTION: In this carrier system of the manufacturing line of semiconductor or liquid crystals for performing conveyance between processes by cassette conveyance and conveyance in a process by sheet conveyance, respectively, running paths 8A, 8B, and 8C of a carrier path 8 in a process are composed independently, in a plurality of steps in upper and lower directions, sheet conveyance vehicles 7A, 7B, and 7C with a placement stand 73 for placing a substrate 6 are arranged at each of the running paths 8A, 8B, and 8C, and at the same time, a load port 9 for simultaneously passing a substrate 6 among the sheet conveyance vehicles 7A, 7B, and 7C at the same position, is arranged along the carrier in-process path 8.