PURPOSE: To contrive highly secrete preservation and handling easiness by providing a cipher decoding part and a storing part large in storage capacity in a watch and sending encipherment data decoding, data display and encipherment data.

CONSTITUTION: An LED 305 is flickered by the use of the input signals of terminals 301, 302 and a phototransistor 306 receives them to convert them into electrical signals. Next an amplification shaping circuit 307 performs the amplification and shaping of a wave form to input into a code control circuit 308 so as to decode a data code. And decoding data are input into a microprocessor MPU 330. This data processing program is stored in a ROM 340 and the processed result in a RAM 341. The data which the MPU 330 reads out from a RAM 341 are encoded in the circuit 308 and a drive circuit 311 converts them into flickering signals of the LED 310 to be applied to a phototransistor 309 to convert into electrical signals so as to display on a data display circuit 364 via an input and output control circuit 342.