The reliability of data is significantly increased without considerably
increasing costs by performing minor data corrections within an
information storage device and performing major error corrections in an
information processing device. When a request to transfer user data for
reading is issued from an information processing device, a control
circuit transfers the user data and management data to an error detection
circuit, which checks the user data for errors. If the user data contains
no error, the control circuit notifies the information processing device
that the user data can be transferred, and transfers it to the
information processing device. If the user data contains errors, an X
count error position and correction data calculation circuit uses the
user data and the management data to calculate correction locations and
correction data, and judges whether the correction locations are
correctable. If uncorrectable (there are more correction locations than X
locations), the control circuit notifies the information processing
device that the user data is uncorrectable, and then transfers the user
data and the management data to the information processing device.