A data processor includes: a data input unit that inputs data in real time; an input data storing unit in which the inputted data is stored; a signal processing unit that reads out the stored data and performs signal processing of the stored data; a signal processing control unit that has the signal processing unit intermittently perform the signal processing faster than real-time; a clock/power source control unit that reduces power consumption by restricting a clock signal and/or electric power to the signal processing unit and the signal processing control unit in an inactive period of the intermittent operation; and an input monitor unit that monitors the volume of stored data, requests the clock/power source control unit to remove a clock or power restriction based on the volume, and requests the signal processing control unit to move into an active period of the intermittent operation.