A signal processing circuit includes a feedback control loop that includes a loop filter and that detects the difference between a target value and a control value to control the difference so that the difference has a predetermined value. A closed loop formed in the feedback control loop is expressed by the delay of the entire closed loop serving as the feedback control loop, the loop filter, and simple integration of a final stage. The signal processing circuit includes a moving average calculating unit configured to calculate a moving average of outputs from the loop filter; a multiplying unit configured to multiply a value calculated in the loop filter by a certain gain; and an integrating unit provided upstream of the loop filter so that calculation results by the moving average calculating unit and the multiplication unit are concurrently fed back to an input into the loop filter.