PURPOSE: To exactly attain transmission error detection by providing newly a means for counting the number of bit data with a prescribed length, and a means for executing an integration at every bit data by said number of bits and executing a two-continuous sending collation only in case an integral value is not a reference value.

CONSTITUTION: The titled device is provided with a means 11 which is provided on a reception side, and counts the number of bit data of a prescribed length of a transmitting data, and two-continuous sending collating means 8∼12 which are provided on the reception side, and discriminate whether each bit data is correct or not with respect to the number of bit data of a prescribed quantity, and execute two-continuous sending collation only when the bit data which cannot be discriminated as it is clearly correct is contained in the number of bit data with a prescribed length. In this regard, by synchronizing with a synchronizing clock of the second clock generator 3A of the reception side, the result of an integration circuit 8 is brought to a comparison operation with a reference value which is stored in advance, by a comparison operating part 9, only when its result is not put in the reference value, the two-continuous sending collation is executed and a data transmission error is detected.