1. A method for localizing an interruption structure included in a hierarchical structure of a specification described in a system description language, the method comprising: specifying an interruptible portion in the hierarchical structure of the specification based on a code of the specification; segmenting the specification into a plurality of parts including no interruptible portion interruptible at the specified interruptible portion; and localizing the interruption structure to the interruptible portion which belongs to lower-level of the hierarchy than the level of the hierarchy at which the interruption structure of the specification is defined.