Disclosed is a near-infrared fluorescent imaging agent that contains an indocyanine fluorescent dye and liposomes. The near-infrared fluorescent imaging agent has high fluorescence intensity and a long anchoring time in sentinel lymph nodes, and so is useful for detecting sentinel lymph nodes in sentinel lymph node navigation surgery. Further disclosed is an indocyanine green derivative that is particularly suitable for use in the near-infrared fluorescent imaging agent.
