1. A display method of a synchronous control program for controlling driving of a multi-axis synchronous control device, wherein in a multi-axis synchronous control system that includes a multi-axis synchronous control device that, upon executing positioning control on a plurality of axes according to a plurality of synchronous control programs that are respectively input to the axes, when settings of driving software modules in the synchronous control programs are same as each other, executes positioning control while synchronizing the axes with each other, a control device that generates the synchronous control programs respectively corresponding to the axes on which the multi-axis synchronous control device executes positioning control, and that outputs the generated synchronous control programs to the multi-axis synchronous control device, and a display device that includes a display screen, and as a step of, by the control device, displaying a the synchronous control programs that are executed by the multi-axis synchronous control device and respectively correspond to the axes on the display screen of the display device, the display method comprises: a displaying step of displaying on one screen a synchronous control program of a multi-axis configuration, in which the driving software modules are coupled together into a same axis, among the synchronous control programs, and the displaying step includes a selecting step of selecting either execution or non-execution of a module operation of each of a plurality of software modules that constitute the synchronous control program of a multi-axis configuration after displaying the software modules on the display screen of the display device in a state where the software modules respectively correspond to a plurality of cells arranged in a matrix, and a rearrangement displaying step of displaying the synchronous control program of a multi-axis configuration in such a manner that software modules having been selected as execution at the selecting step are directly connected to each other by removing cells that correspond to software modules having been selected as non-execution at the selecting step, while storing a coupling relationship between the software modules having been selected as execution at the selecting step.