To provide a demodulation circuit, a processing circuit, a processing method, and a processing device that are capable of implementing more prompt acquisition of alert information. Provided is a demodulation circuit including a demodulation unit configured to demodulate a broadcast signal received by a reception circuit that receives the broadcast signal, a determination unit configured to determine whether or not acquisition of alert information included in the demodulated broadcast signal is necessary according to a set operation mode, on the basis of first alert notification information indicating an update state of the alert information included in the demodulated broadcast signal, and an output processing unit configured to output second alert notification information corresponding to the operation mode from a predetermined terminal to which a processing circuit having a function to acquire the alert information is electrically connected, in a case where acquisition of the alert information is determined to be necessary.