PURPOSE: To prevent sweeping from being stopped in error due to the modulation (modulation frequency) of a broadcast wave at the sweeping by providing a means decreasing the AGC response time constant and switching its time constant to a value at the normal operation in obtaining a tuning detection signal.

CONSTITUTION: The AGC circuit 20 is brought into the operating state even in the automatic frequency sweep state and in such a case, the time constant of the AGC circuit 20 is decreased more than that at the steady-state. When automatic frequency sweeping is conducted and a broadcast signal is turned, an intermediate frequency is obtained and it is counted by a counter 21 and when the counting reaches a prescribed number, a detection signal is obtained from the detection circuit 22 and fed to a system controller 23. Then the system controller 23 brings the time constant of the AGC circuit 20 to a value at the steady state. Then in the presence of key entry for channel selection, the system controller 23 inhibits the signal reception from the detection circuit 22 for a prescribed period (e.g., one step variable period) to initiate the automatic frequency sweeping and the time constant is switched and the sweeping is stopped.