To provide a method for prolonging life of a flash memory by using a block continuously which is actually not abnormal even with respect to a block in which a write counter value or read counter value is equal to or larger than a threshold.

The method for prolonging life of the flash memory includes: a copying step of copying data of a block where the write frequency or read frequency is equal to or larger than a prescribed value to a certain block included in a group of spare blocks; an availability step of using a block of a copying party instead of a block of a copied party; and a spare block addition step of adding the block of the copied party to the group of spare blocks.