PURPOSE: To cause no malfunction for any frequency, by providing a two state storing means whose storing state is switched complementarily in accordance with the outputs of the first and the second frequency discriminating means.

CONSTITUTION: A titled device is provided with a two state storing means whose storing state is switched complementarily in accordance with the first frequency discriminating means output and the second frequency discriminating means output. At the time of reception of 50Hz, a -Q output of an FF8 sometimes causes a malfunction and becomes a high level. Also, at the time of reception of 60Hz, a -Q output of an FF81 sometimes causes a malfunction and becomes a high level. Even is case when a malfunction occurs in this way, however, an exact discriminating signal 9 is obtained from an RS-FF13. In this regard, in case when a noise is mixed at the time of receiving a 50Hz signal, sometime an output of the FF81 also executes a malfunction, but unless it coincides with a malfunction of the FF8, no malfunction output appears in the final discriminating output 9. In this way, it is possible to scarcely cause a malfunction even in case of any frequency.