A novel near-infrared dye-bound transferrin exhibiting a high absorption coefficient in the near-infrared wavelength region, a high tumor accumulation property, a high tumor/blood ratio and a high imaging contrast, and a contrast agent for photoacoustic imaging, including the same are provided. A compound is provided in which transferrin and an organic dye having a specified structure that absorbs light in the near-infrared wavelength region are covalently bound.