There is provided, for example, a food quality examination device configured to inspect the quality of food with high sensitivity using an InP-based photodiode in which a dark current is decreased without a cooling mechanism and the sensitivity is extended to a wavelength of 1.8 μm or more. An absorption layer has a multiquantum well structure composed of a III-V group semiconductor. A pn junction is formed by selectively diffusing an impurity element into the absorption layer. The concentration of the impurity in the absorption layer is 5×1016/cm3 or less. A diffusion concentration distribution control layer composed of III-V group semiconductor is disposed in contact with the absorption layer on a side of the absorption layer opposite the side adjacent to the InP substrate, the bandgap of the diffusion concentration distribution control layer is lower than that of the InP, the diffusion concentration distribution control layer has an n-type impurity concentration of 2×1015/cm3 or less before the diffusion, the diffusion concentration distribution control layer having a portion adjacent to the absorption layer, and the portion having a low impurity concentration. The food quality examination device receives light having at least one wavelength of 3 μm or less within the absorption band of water, thereby performing the inspection.