PURPOSE: To freely perform the card applications while keeping the confidentiality, by detecting the disagreement with the recording form set and sisabling the delivery of read-in data.

CONSTITUTION: The identification of cards used for specific subscribers are constituted that the specific symbol X is described on the nth character of the data section. The clock and data on card is read in, the counter 9 counts the timing signal consisting of the clock, and the output is taken as the input enable signal to the data buffer 15, it is compared with the output of the memory circuit 10 storing the specific character location at the comparison circuit 11, which produces an output when in agreement. On the other hand, X is stored in the memory circuit 12, it is compared with the output of the register 3 at the comparator 13, and a signal is outputted when the both are not in agreement. The AND gate 14 is open when coincidence signal is outputted from the comparator 13 when the agreement signal is outputted from the comparator 11, to clear the buffer 16 and to inhibit the setting of data afterward.