PURPOSE: To secure an automatic stop of a tape recorder, by detecting that the input signal to be recorded has discontinued for a fixed time through the rectifying circuit and the holding circuit.

CONSTITUTION: The input signal of the input terminal 1 is recorded on the magnetic tape by the magnetic head 3 via the amplifying circuit 2. The output of the circuit 2 is supplied to the circuit block 5 via the amplifying circuit 4 and supplied to the holding circuit T after rectified at the circuit bolck 5. The circuit T delivers a constant level regardless of a temporary discontinuation of the input. In case the input is discontinued for a fixed time or more, the output of the block 5 becomes lower than the fixed level. Thus the Schmitt circuit 6 has an inverting action, and accordingly the switching circuit 8 is actuated by the control circuit 7. Then the plunger 9 works in case the switch 10 is turned on to put the tape recorder under the pause mode.