1. A method for identifying a cancer lesion, the method comprising: intravenously injecting indocyanine green to a living body and allowing the indocyanine green to accumulate in the cancer lesion; surgically exposing a target organ suspected of having cancer and irradiating the target organ with excitation light of indocyanine green, and causing the indocyanine green to emit near infrared fluorescence radiation; imaging the target organ to generate a near infrared fluorescence image, wherein the imaging of the target organ is carried out at least 1 day after the administering of the indocyanine green to the living body; and identifying with the near infrared fluorescence image an area having the near-infrared fluorescence radiation as the cancer lesion in the target organ, wherein the target organ is a liver.