PURPOSE: To provide a read data output device whose control program, etc., can be easily generated, and in addition, the secrecy of whose enciphering method can be maintained.

CONSTITUTION: This read data output device 1 is provided with a first file 2a in which the control program is stored, a second file 2b in which a conversion table is stored, and a converting part 4 to encipher inputted read data by referring to the conversion table in conformity with the control program. Since the conversion table is stored in the second file 2b separate from the file for the control program, the control program can be managed by generating only one kind of it even if the enciphering method is different, and besides, a user can generate only the conversion table and store it in the second file 2b while maintaining the secrecy of the enciphering method.