1. A method for storing data in a non-volatile memory, comprising the steps of: writing data into a plurality of memory regions of said non-volatile memory to which data is able to be written a limited number of times, said plurality of memory regions including an initial memory region and a final memory region, each of the memory regions being assigned a serial address, the initial memory region being assigned the first address among the serial addresses, the final memory region the last address among said serial addresses, and the final address being followed by the initial address to permit circular access of said non-volatile memory, said plurality of memory regions being equal or greater in number than a value determined by dividing the number of times data is to be written into said non-volatile memory by said limited number of times, and each of said plurality of memory regions having a writing count number storing region for storing a writing count number and a data storing region for storing data; searching said plurality of memory regions to locate an effective memory region defined as that memory region which has the last serial address among a group of said memory regions storing a writing count number equal to that stored in said initial memory region; writing a writing count number and data into a writing count number storing region and a data storing region, respectively, of a memory region which has an address next following that of amid effective memory region, said writing being performed without erasing data from said effective memory region, said writing count number having a value which is one greater than said writing count number stored in said initial memory region if said effective memory region is said final memory region, and writing a writing count number which is the same as that stored in said writing count number storing region of said initial memory region if said effective memory region is not said final memory region; and reading data from said effective memory region.