The present invention relates to an optical imaging probe for detecting a sentinel lymph node, which contains a complex of poly-gamma-glutamic acid and an optical imaging dye, and more particularly to an optical imaging probe for detecting a sentinel lymph node, which contains a poly-gamma-glutamic acid/optical imaging dye complex that, when injected subcutaneously in vivo, remains in the sentinel lymph node for a relatively long period of time and has a low tendency to migrate to other lymph nodes. The present invention provides a poly-gamma-glutamic acid/fluorescent dye complex, which contains no radiopharmaceutical and is harmless to the human body. The use of the poly-gamma-glutamic acid/fluorescent dye complex makes it possible to accurately detect the position of a sentinel lymph node in real time without concerns about radioactive contamination.