A laser processing system including a laser processing unit, a controller controlling the processing unit according to a laser processing program, and a restart preparation apparatus performing a preparation process of the controller to resume the program execution after being suspended. The restart preparation apparatus includes an operating state judging section judging whether an operating state of the processing unit when suspending the program execution is in course of laser processing, and a restart condition specifying section specifying a restart condition of the processing unit when resuming the program execution, from among predetermined conditions, based on a judgment result. The operating state judging section judges that the operating state is in course of laser processing, if a predetermined operation command for processing the workpiece is output from the controller, or predetermined external information for processing the workpiece is input to the controller, at the instant of suspending the program execution.