Disclosed herein is a data processing apparatus including: an adjusting section configured to receive a stream including packets and a start flag indicative of the beginning of each of the packets in the stream, adjust a rate of the stream to a certain rate, and output the adjusted stream that is the stream after the rate adjustment and the start flag indicative of the beginning of each of the packets in the adjusted stream; a monitoring section configured to monitor a packet interval that is a start interval between the packets in the adjusted stream on the basis of the start flag; and an output control section configured to execute output control of outputting the packets in the adjusted stream if the packet interval is a normal interval and restricting the outputting of the packets in the adjusted stream if the packet interval is an abnormal interval.