An instruction conversion apparatus for optimizing an instruction program formed of a plurality of instructions to be suitable for execution by a microprocessor that has a plurality of hard ware resources. The apparatus includes a power control information analysis unit for detecting a power controllable hardware resource that does not operate for a certain specific instruction region in the instruction program while the microprocessor is at work, and a power control instruction providing unit for providing the instruction program with an instruction regarding the power control based on the result of the detection made by the power control information analysis unit.