PURPOSE: To attain asynchronous connection in each station and to reproduce a signal including waveform distortion and jitter also as a synchronized data, by supplying a clock having suitable timing to a data sent asychronously.

CONSTITUTION: Three reading-out circuits 31∼33 are used and the circuit 31 reads out serial data 15 by using a trigger 19. NRZ data 34 outputted from the circuit 31 is supplied to a circuit 32. A clock signal 36 selected from a clock selecting circuit 35 is supplied to the circuit 32. The signal 36 has freqency equal to that of an office clock signal 22 outputted from a system clock gennerator 21, but the rise timing is set up so as to be suitable for the reading out of the data 15. The signal 36 is set up by selecting the signal 36 from plural clock signals 38 of which phases only are different each other on the basis of an edge detecting data 37 supplied from an edge detecting circuit 16 to the circuit 35.