A detection signal processor that includes a signal processing unit, bias current supply components, and a bias current control component is provided. The signal processing unit applies a first signal processing in parallel to plural detection signals input in parallel, converts the plural detection signals to serial detection signals by applying a parallel-to-serial conversion processing to the plural detection signals, and applies a second signal processing to the converted serial detection signals in turn. The bias current control component switches amount of the bias currents supplied to the each circuit configuring the signal processing unit by the bias current supply components, the bias currents including first bias currents supplied to the first circuits carrying out the first signal processing and second bias currents supplied to the second circuits carrying out the parallel-to-serial conversion processing and the second signal processing in turn.
