PURPOSE: To stabilize the change of the tape travelling speed based on the load fluctuation of the tape reel, by assuming a differential speed control.

CONSTITUTION: The pulse-type speed signal (a) supplied from the speed detector 14 is applied to the frequency discriminator 21 and then turns to the plus/minus voltage change to the reference speed as the detection output (b) of the frequency change of (a). At the same time, the front edge of the signal (a) is detected by the monostable multivibrator 22 to be turned to the gate pulse (c). The pulse (c) controls the sampling circuit 23, and as a result the waveheight value according to the change of speed is held at the charge/discharge circuit consisting of the capacitor 24 and the resistor 25. On the other hand, the output (b) is levelled by the low pass filter 26 to be turned into the average speed signal (d). The signal (d) and the charge/discharge output (e) are added together by an adder, and this output is applied to the drive amplifier 29 in the form of the speed change suppression signal.