A signal charge collecting region is disposed inside a charge generating region so as to be surrounded by the charge generating region, and collects signal charges from the charge generating region. An unnecessary charge collecting region is disposed outside the charge generating region so as to surround the charge generating region, and collects unnecessary charges from the charge generating region. A transfer electrode is disposed between the signal charge collecting region and the charge generating region, and causes the signal charges from the charge generating region to flow into the signal charge collecting region in response to an input signal. An unnecessary charge collecting gate electrode is disposed between the unnecessary charge collecting region and the charge generating region, and causes the unnecessary charges from the charge generating region to flow into the unnecessary charge collecting region in response to an input signal.