1. An encryption key setting device configured to set an encryption key, comprising: a code string inputting system configured to receive an external input of a code string; a code number determination system configured to determine whether the inputted code string includes a total number of codes less than a specified number or includes a total number of codes equal to or greater than the specified number; a generating procedure selecting system configured to receive an external input for selecting any one from a plurality of generating procedures that were previously set responsive to the code number determination system determining that the inputted code string includes a total number of codes less than the specified number; a code string generating system configured to generate a code string using the code string inputted through the code string inputting system based upon the generating procedure selected through the generating procedure selecting system; a first encryption key setting system configured to set the code string generated through the code string generating system as the encryption key; a specified input receiving system configured to receive an external specified input that was previously set; and a second encryption key setting system configured to forbid an operation of the first encryption key setting system when the number of codes included in the code string inputted through the code string inputting system is equal to or more than a specified number that was previously set, and set the inputted code string as the encryption key.