PURPOSE: To improve the sensitivity of a blue color, by making the concentration or the depth of a diffused layer constituting a photodiode different from those of diffused layers at other parts.

CONSTITUTION: The concentration of an N-type diffused layer 6 constituting a photodiode formed on a P-type Si substrate 1 is made thinner than those in N-type diffused layers 3 and 8 constituting an MOS transistor. Or the depth of the layer 6 is made shallower than those of the layers 3 and 8. When the concentration of the layer 6 is made thin, the lifetime of minority carriers in the layer 6 is increased, and the sensitivity of a blue color is improved. When the depth of the layer 6 is made shallow, the amount of the blue color component absorbed in the layer 6 is decreased, and the blue color sensitivity can be enhanced.