A first conveyor belt and second conveyor belt are disposed on guide rail which is disposed so as to extend in a circuit substrate conveyance direction. Then, the circuit substrate supported by both the conveyor belts of the first conveyor belt and the second conveyor belt is held by substrate holding device, and work is performed on the held circuit substrate. In the transfer device having such a structure, for example, when the circuit substrate on which an operation has been completed is conveyed out by the second conveyor belt, a new circuit substrate is conveyed into the transfer device by the first conveyor belt. In this way, it is possible to perform printing work on a new circuit substrate at an early stage and shorten a cycle time.