PURPOSE: To confirm the reception of a specific code in a short time with high precision by adding the subtracting a specific numeral to and from a counted value corresponding to the specific code according to whether a received code coincides with the specific code or not, and comparing the obtained result with a threshold value.

CONSTITUTION: When the received code is stored in a receiving buffer 41, a collating circuit 42 selects on code register 44 through a selecting circuit 43 and the specific code in the register 44 is collated with the received code stored in the buffer 41. When they coincide with each other, an α adding circuit 45 is driven to add α to the counted value of a counting register 48 and when not, a β subtracter 46 is driven to subtract β from the value of the register 48. On the other hand, (m) sets of comparing circuits 49 provided corresponding to registers 48 compare the threshold values set in (n) sets of threshold value registers 50 with the counted values of the registers 48. When the counted values exceed the threshold values, the specific code stored in the register 44 is transferred to a confirmation buffer 51 and transmitted to following devices.