1. A data processing device comprising: a set associative type cache memory which stores cache entries in a plurality of ways, wherein when reading cache tags, the cache memory selects, from among the plurality of ways, part of the ways according to a value of select data created based on tag address information which is part of address information, and reads cache tags from the selected ways by use of an index address in the address information, and when performing cache fill, the cache memory performs the cache fill on a cache entry selected from part of the ways according to the value of the select data.