A game machine controller according to the present invention is provided with a memory pack equipped with a nonvolatile memory. The memory pack is able to store a plurality of commands designated by a predetermined button operation as command programs. Once the data is stored, it is retained unless it is compulsorily rewritten or deleted. The command program stored in the memory pack is retrieved and executed by a simple operation of the command buttons. The memory pack can be attached and detached freely so that it can conform to each software. As a result, once the command programs are stored, there is no need to renew the command programs every time the game software is replaced.