A controller support device for simulation of a control program including a sequence control portion and a motion control portion executed for every control period in a controller for controlling movement of a machine, the controller support device comprising: a simulation unit configured for simulating execution of the control program and generating execution result data; a display data creating unit configured for creating display data for displaying temporal change in the execution result data generated by the simulation unit; an accepting unit configured for accepting an instruction of a user on the simulation unit; and a display for displaying the display data created by the display data creating unit; wherein the simulation unit includes: a sequence calculation executing part configured for simulating execution of the sequence control portion of the control program and generating execution result data related to the sequence control portion, a sequence variable storage part configured to be used by the sequence calculation executing part for executing the simulation, a motion calculation executing part configured for simulating execution of the motion control portion of the control program and generating execution result data related to the motion control portion, a motion variable storage part configured to be used by the motion calculation executing part for simulating execution, and characterized by a control period counting section configured for counting a number of executions of the control period, and a resuming data storage section configured for saving: resuming data including data of the number of executions corresponding to a resumable control period in which re-execution of the simulation can be started, and variable data used to start the re-execution of the simulation from the resumable control period, the variable data being data stored in the sequence variable storage part and the motion variable storage part in the control period previous to the resumable control period; the simulation unit configured to: specify the resumable control period, and store the resuming data corresponding to the resumable control period in the resuming data storage section; and the simulation unit configured to acquire a specification for specifying the control period to start the re-execution from the accepting unit, and to specify the control period to start the re-execution using the specification, and to start the re-execution of the simulation from the specified control period using the saved resuming data corresponding to the specified control period. a simulation unit configured for simulating execution of the control program and generating execution result data; a display data creating unit configured for creating display data for displaying temporal change in the execution result data generated by the simulation unit; an accepting unit configured for accepting an instruction of a user on the simulation unit; and a display for displaying the display data created by the display data creating unit; a sequence calculation executing part configured for simulating execution of the sequence control portion of the control program and generating execution result data related to the sequence control portion, a sequence variable storage part configured to be used by the sequence calculation executing part for executing the simulation, a motion calculation executing part configured for simulating execution of the motion control portion of the control program and generating execution result data related to the motion control portion, a motion variable storage part configured to be used by the motion calculation executing part for simulating execution, and characterized by a control period counting section configured for counting a number of executions of the control period, and a resuming data storage section configured for saving: resuming data including data of the number of executions corresponding to a resumable control period in which re-execution of the simulation can be started, and variable data used to start the re-execution of the simulation from the resumable control period, the variable data being data stored in the sequence variable storage part and the motion variable storage part in the control period previous to the resumable control period; resuming data including data of the number of executions corresponding to a resumable control period in which re-execution of the simulation can be started, and variable data used to start the re-execution of the simulation from the resumable control period, the variable data being data stored in the sequence variable storage part and the motion variable storage part in the control period previous to the resumable control period; specify the resumable control period, and store the resuming data corresponding to the resumable control period in the resuming data storage section; and the simulation unit configured to acquire a specification for specifying the control period to start the re-execution from the accepting unit, and to specify the control period to start the re-execution using the specification, and to start the re-execution of the simulation from the specified control period using the saved resuming data corresponding to the specified control period.