A data storage device executes a program including the steps of: determining whether or not a storage instruction to include data to be stored, along with a class generated as a label common among application software, has been obtained; detecting a class in the contents of the storage instruction when the storage instruction is obtained; determining a storage manner based on the class and a table defining in advance storage manners; and storing data in an appropriate storage medium with appropriate data redundancy based on the determined storage manner.