To provide a search key optimization apparatus and a search key optimization program which can secure the quality of a response in DB access without increasing a workload of a designer.

The search key optimization apparatus which optimizes search keys used for the search of a DB by a program logic 21 comprises: a first search key-extracting means 10 which extracts one or more search keys used for searching the DB from the program logic 21; a second search key-extracting means 11 which extracts one or more search keys from a DB-defining element 22 in which previously defined search keys are defined; and a means of checking the propriety of the search keys 13, 14 and 15 which use the information of a priority order 25 in which the priority order for use in search is set for each item of the DB constituting the search keys, the check propriety of the search keys extracted by the first search key-extracting means 10, and update the DB-defining element 22 by the search keys in which the check of the propriety has been correctly completed, thus solving the problem.