By selectively anisotropically etching a stack film formed to cover a plurality of photodiodes and a gate electrode layer of a MOS transistor, the stack film remains on each of the plurality of photodiodes to form a lower antireflection coating and the stack film remains on a sidewall of the gate electrode layer to form a sidewall Using the gate electrode layer and the sidewall as a mask, an impurity is introduced to form a source/drain region of the MOS transistor. After the impurity was introduced, an upper antireflection coating is formed at least on a lower antireflection coating At least any of the upper antireflection coating and the lower antireflection coating is etched such that the antireflection coatings on the two respective photodiodes are different in thickness from each other.