PURPOSE: To easily change instruction executing forms by installing an instruction execution controlling table in which executing forms of each instruction of a robot language are specified to a memory and executing each execution routine based on data read out from the table.

CONSTITUTION: A control program 11, operation program 12, instruction execution controlling table 13, execution routines 14W16, operating instruction execution routine 17, and servo processing routine 18 are stored in a memory 10 and connected with a CPU20. First, a signal 23 is outputted to the program 12 from the CPU20 in accordance with a command 21A from the program 11 and data PD are read out. When the program 11 discriminates that no terminating command is given, the program 11 gives another command 21B to the CPU20 to read out data OD from the table 13 and lets the CPU20 make a corresponding processing after discrimination. Therefore, the executing form of an instruction can be changed by changing the data of the table 13.