Provided is a biological component detection device with which a biological component can be detected at high sensitivity by using an InP-based photodiode in which a dark current is reduced without using a cooling mechanism and the sensitivity is extended to a wavelength of 1.8 μm or more. An absorption layer 3 has a multiple quantum well structure composed of group III-V semiconductors, a pn-junction 15 is formed by selectively diffusing an impurity element in the absorption layer, and the concentration of the impurity element in the absorption layer is 5×1016/cm3 or less, 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, the portion having a low impurity concentration. The biological component detection device is characterized in that an examination is conducted by receiving light having at least one wavelength of 3 μm or less, the wavelength being included in an absorption band of the biological component.