A program preparation apparatus that can reduce power consumption and that can suppress malfunctions and the occurrence of noise by improving software is provided. An assembler prepares a relative object program based on an assembly source program. Next, the assembler changes the order of instructions included in the assembly source program in a range that does not influence the operational results in a CPU and, thereby, prepares another assembly source program so as to prepare a relative object program based on this assembly source program. Next, the assembler finds the respective maximum Hamming distance values between respective instructions for a plurality of relative object programs so that the program of which the maximum Hamming distance value is the lowest is determined as a formal relative object program.