Nonvolatile memory device employing a write completion flag table

A semiconductor memory device, comprising:

• a non-volatile main storage memory including a plurality of physical blocks, each physical block having a plurality of storage capacity units composed of a data region in a first storage capacity and a management region;
• an address management information storage that stores address management information of said main storage memory and a block status of each physical block indicating whether data stored in the block is valid or not;
• a non-volatile control memory that stores a writing completion flag table which is provided to said main storage memory every second storage capacity smaller than said first storage capacity and consists of writing completion flags placed when data writing is completed to each of said second storage capacity;
• and
• a controller that performs read/write control for said main storage memory in accordance with a direction of data read/write from a host and for performing update control for said address management information storage part and said non-volatile control memory.