1. A cache memory observation device for observing a cache access executed to a cache memory comprising a plurality of cache entries comprising: a cache miss judger for judging a cache miss when the cache access is executed; an entry region judger for judging which of a plurality of entry regions constituted with one or a plurality of cache entries in the cache memory is accessed by each of the cache accesses using at least a part of an index for selecting an arbitrary cache line in the cache memory; and a cache miss counter for counting number of the cache misses judged by the cache miss judger in each of the entry regions which is made to correspond to each of the cache accesses by the entry region judger.