An encoding program causes a computer to execute a process of inputting thereto a CSV file having a plurality of records each including a plurality of item which are separated by a delimiter. The encoding program causes the computer to execute a process of generating an encoded file having encoded data and an encoded dictionary each in which a specific item included in the records of the input CSV file is encoded by word or numerical value. The encoding program causes the computer to execute a process of generating an encrypted file including an encrypted dictionary in which the encoded dictionary is encrypted, from the generated encoded file.