Step data are sequentially read out from a conversational program created in a conversational format. The processor 13 determines whether or not leaning control in the step is possible. When the leaning control is possible, a learning start command is added to the start of the program to create and output an NC program in the step. Also a learning end command is added to the end of the NC program in the step. Conversion into the NC program is performed for each of steps. When a learning control automatic ON/OFF operation is selected to all the steps, a learning control start command and a learning control end command are added to the start and the end of the converted NC program when learning control of all the steps can be performed.