A linker generates a simulator-use executable format program from a pre-conversion object program and a simulator-use object program. A simulator executes the simulator-use object program and acquires branch trace information. A binary program converting tool, based on the branch trace information and a branch penalty table, generates a post-conversion object program having a rewritten branching prediction bit of the pre-conversion object program. Another linker generates an actual-machine-use executable format program from the post-conversion object program and an actual-machine-use object program.