PURPOSE: To provide a preparation method of a sequencer control program for converting a program prepared by making the depth of a sequence memory and the depth of a data memory look the same to a programmer to the program not provided with test data.

CONSTITUTION: The program whose rows are constituted of the respective fields of 'label', 'instruction', 'hardware mode' and 'data' prepared in a virtual memory space whose depth is the same as the one of the data memory 3 is converted to the program (composed of the respective fields of 'instruction', 'hardware mode', 'starting address' and 'ending address') for address specifying information inside the 'data' field stored in the data memory 3.