The present invention provides ligand detection means capable of exhibiting two-dimensional information (wavelength and intensity of luminescent signal) responding to multiple signals triggered by a ligand via a target protein, while taking advantage of the merit of the single-molecule-format bioluminescent probe. The present invention could provide a luminescent probe set which is comprised of a fusion protein comprising a ligand recognition protein and a molecular recognition domain to which the ligand recognition protein bind upon conformational change, wherein the fusion protein is sandwiched between split Lighting Enzyme fragments, the probe set can emit multiple luminescence by utilizing Lighting Enzymes emitting lights with multiple wavelength, wherein these multiple components can be tandemly arranged by using C-terminal fragment of the Lighting Enzyme. By using a living cell line transfected with gene of multicolor luminescent probe set or single-molecule-format multicolor bioluminescent probe, it becomes possible to distinguish and detect bioactivity level of a target ligand in a complex context of the living cell two-dimensionally (wavelength versus intensity) in multi colors, and to quantitatively evaluate multiple effects (anticancer and carcinogenesis actions, agonist and antagonist) of a ligand represented by a drug at once by two-dimensional information of different colors in short time.