A transfer system includes a transfer module extending along a first direction, a plurality of processing modules connected to the transfer module and provided along a direction in which the transfer module extends, and a loader module connected to the transfer module and extending along a second direction orthogonal to the first direction. The loader module includes a main housing having a load port configured to load a transfer target into the loader module, and a sub-housing formed separately from the main housing and smaller than the main housing and connected to the transfer module in the second direction of the main housing. The second direction is a direction parallel to a carrier conveyance line for conveying a carrier configured to accommodate the transfer target.