PURPOSE: To enable high-speed control by making clocking operation active when the monitor timer value of control data specified with specific information is significant, and storing the specification information of next control data in a specific area under specific conditions.

CONSTITUTION: In a data group area 104, the monitor timer value, input conditions, next step conditions, branch control data specification information, etc., are stored. Then control data is specified on the basis of information stored in a control data specification area 106 from the data group and when the monitor timer value of the specified control data is significant, the clocking operation of a monitor timer is made active. Information specifying the control data of a next operation step is stored in the control data specification area 106 on condition that conditions of movement to the next step of the specified control data are met and the monitor timer is not in the time-up state. When the monitor timer is in the time-up state, a sequence program which registers abnormality is repeatedly executed.