The present invention provides a signal processing device for removing image noise. The device includes a first storage part for recording first image data captured from a field of view, a second storage part for recording second image data captured under a different light-receiving condition, and a processing part for reading and performing data processing on the first and second image data. Particularly, the processing part determines the noise situation of each pixel in the image sensor, and in accordance with the noise situation, selectively performs, pixel by pixel, the replacement processing for replacing an output value of the first image data with an output value of a proximate pixel of the same hue as the first image data, and subtracting processing for subtracting the output value of the second image data from the output value of the first image data.