Program conversion device, and secret keeping program

To provide a method of generating illegal secret can not easily parse parse the original program of the program conversion apparatus to maintain the program. Obtaining program conversion apparatus generates substituting the first command group into a plurality of selected values ​​of parameters; comprising the plurality of selected parameters using the arithmetic expression, to obtain the first command group indicates a next selection object identifier selection process data 2 instruction group; the selection parameter values ​​reflect indicates selection objects processed in the past selected identifier data, or past substituted into the calculation formula of the above selected value of the parameter a at least one selected parameter to a third command value group; and with the same order of the original program by a predetermined process execution result is output, and selection object data corresponding to a plurality of selected different identifiers, comprising generating a first command group, the second group of instructions, the third group of instructions of said plurality of selected secret object data retention program.