To improve focusing when subject luminance is low without complicating the image processing algorithm.

When the subject luminance is higher than a threshold at the time of focusing, picture signals are outputted independently from respective photoelectric transducing devices α and β of each pixel 'B', 'G1', 'G2', and 'R' (drawing 4 (a)). On the other hand, when the subject luminance is lower than the threshold, the electric charges of photoelectric transducing devices αand β of the pixels 'B' and 'G2' are added respectively and then outputted, and the electric charges of the photoelectric transducing devices α and β of the pixels 'G1' and 'R' are added respectively and then outputted (drawing 4 (b)). At the time of the imaging, the electric charges generated in the photoelectric transducing devices α and β of each pixel 'B', 'G1', 'G2', and 'R' are added within each pixel and then outputted (drawing 4 (c)).