1 ) An optimization compiler comprising: an update instruction detecting section that detects, in a target program to be optimized, an update instruction to update a content of a variable or a content of a storage area specified by a variable; a series of instructions detecting section that detects a series of instructions in said target program, the series of instructions executes a different process corresponding to the content of said variable or the content of said storage area in response to control shifting to the process by a control shift instruction to shift the control to a different series of instructions; a series of instructions compile section that compiles the detected series of instructions by optimizing the series of instructions for a process executed if said variable or said storage area has a predetermined particular content; and a set instruction generating section that generates a set instruction to set a destination address in said control shift instruction to an address of said series of instructions optimized by said series of instructions compile section, the set instruction being executed between said update instruction and said control shift instruction in said target program if said variable or said storage area has said particular content.