It is possible to improve workpiece machining efficiency by efficiently receiving and delivering a workpiece from/to each workpiece holder and shortening a time required for workpiece conveyance. A workpiece conveyance system is a workpiece conveyance system that receives and delivers workpieces W to be machined to n spindles (workpiece holders, where n is an integer satisfying n≥2) that hold and rotate the workpieces W, and includes a main loader including n+m main loader chucks (where m is an integer satisfying m≥1) that receive and deliver workpieces from/to the n spindles or n relay loaders disposed corresponding to the n respective spindles to receive and deliver the workpieces W from/to the main shafts.