To provide a transport vehicle system which does not require many cables for giving and receiving signals between a controller and a transport vehicle.

A controller 50 includes an operation part such as a keyboard 51, a display 52 or the like, a CNC control part and a serial control part. Servo motors 10-30 loaded on a transport vehicle 60 are operated by servo amplifiers 10-30 to drive a traveling shafts (rail RL, a wheel WH10, WH20) of the transport vehicle 60, a work lifter or the like. The servo amplifiers 10-30, an I/O 61 for the transport vehicle are sequentially put in the connecting state by a signal line D12 or the like to form a daisy-chain slave unit taking the controller 50 as a master unit. Various commands, a return signal, an I/O signal and so on are given and received between the controller 50 and each slave unit of the transport vehicle 60 by a serial optical signal using an optical cable OF, the signal line D12 and so on by a daisy chain system.