The invention contemplates to improve versatility or flexibility of a system for managing a controller. In a data format converter, a computer constitutes reception unit for acquiring input information containing a program, etc, of a first data format and outputted from a programmer unit, direction extract unit for extracting a convert direction of a data format contained in the input information so acquired, data conversion rule acquisition unit for acquiring a conversion rule of a data format corresponding to the convert direction so extracted and convert execution means for converting the program, etc, of the first data format to a second data format. The program, etc, of the second data format converted is outputted to the controller. The program, etc, can be created in this way in an arbitrary data format different from the data format of the controller.