According to one embodiment, a photodiode includes a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type, a third semiconductor layer of the first conductivity type, and a film. The second semiconductor layer is provided in the first semiconductor layer. The third semiconductor layer is provided in the first semiconductor layer so as to surround the second semiconductor layer. Each of one ends of the second and third semiconductor layers is located at an upper surface of the first semiconductor layer. The first to third semiconductor layers include first to third impurity concentrations respectively. The second and third impurity concentrations are higher than the first impurity concentration. The film is provided above the third semiconductor layer, and blocks light to enter into a neighborhood of the third semiconductor layer.