A security assurance technique for electronic information wherein an electronic information file 1 is divided into a plurality of information elements 2 and the divided information elements are selected and combined with their order changed to produce one or more information blocks 3, and division extraction data of the information elements is produced and the information blocks are formed and stored or transmitted, whereafter, when the electronic information is to be utilized, the information elements 4 included in the information blocks 3 are re-divided, re-arranged in the correct order and integrated based on the division extraction data to restore an original electronic information file 5, whereby, even if electronic information stored or being communicated is stolen, the value of the information is reduced to disable utilization of the information.