PURPOSE: To obtain a signal which has small amplitude fluctuations and small phase fluctuations and to improve the S/N of a signal wave by dividing and connecting a continuous signal, and delaying the connected signals continuously and connecting them with time.

CONSTITUTION: A switch 4 for dividing the signal, a 1st delay part consisting of plural delay devices 5 through which the divided signals are passed, an adder 8 which connects all the divided signals after they are put in phase through the delay devices 5, and a 2nd delay part consisting of plural delay devices 7 which input the output of the adder 8 are provided. Then the signals which are outputted by the 2nd delay part on a time-division basis are connected with time. Thus, the divided signals are all connected to average amplitude fluctuations and phase fluctuations that the signals have respectively, thereby obtaining the signal which has small amplitude fluctuations and small fluctuations.