NONVOLATILE SEMICONDUCTOR STORAGE DEVICE

PROBLEM TO BE SOLVED: To provide technology for efficiently avoiding read disturbance.SOLUTION: A nonvolatile semiconductor storage device (1) includes a nonvolatile storing part (11), and a controller (12) capable of controlling refresh processing for rewriting data of each block to be an erasure unit of the nonvolatile storing part in a block different from the block. The controller sets a first region and a second region different from the first region in the nonvolatile storing part, and executes refresh processing about the first region and the second region each time a refresh trigger is generated so as to make a refresh frequency about data of the first region higher than a refresh frequency about data of the second region. This can efficiently avoid read disturbance when read access is repeated.