To provide a digital signal processor which reduces costs of a worker and also suppresses the variation of adjustment results at the time of adjusting an output level.

In this digital signal processor, when a video signal is outputted from a line I/O 2, an output signal from an output buffer 1 is inputted to a voltage control amplifier(VCA) 7 through an input buffer 3. The VCA 7 amplifies an input signal with a gain that corresponds to the voltage of a battery 12, and a sink level detection circuit in a digital signal processing circuit 6 outputs a detected sink level to a control circuit 9. The circuit 9 generates gain control voltage based on the inputted sink level and inputs it to a control terminal of a D/A converter 5. The converter 5 operates to vary gain according to the gain control voltage, and the circuit 9 operates to make the sink level that is outputted from the line I/O 2 constant.