PURPOSE: To make the device miniaturized and low-priced by providing corresponding numbers of shift registers, how many the number of replacement time slots may be, and miniaturizing a circuit size than heretofore.

CONSTITUTION: A serial input data is inputted to a shift register 1, and a timing signal indicating the time slot position to be replaced in an input data is transferred to the shift register 1 from a selector 3 by way of an OR gate 5, and a data of a time slot position to be replaced is read by the shift register 1. A timing circuit 4 transfers a timing signal indicating the time slot position to be replaced to the shift register 1 by way of the OR gate 5, and shifts a data read by the shift register for outputting. A timing signal of the time slot position to be replaced is obtained by selectively making connections by the selector 3 among timing signals indicating each time slot position of the input data transmitted by a timing circuit 2.