Abstract: The present invention relates to a novel coumarin derivative, to a method for preparing the same, and a multi-fluorescent substance that includes a plurality of the coumarin derivatives and is able to emit light using an LED light source. A novel coumarin derivative multi-fluorescent substance according to the present invention has an optimal emission wavelength band of 512 nm to 590 nm and thereby is effective in improving a signal intensity and stability since light emission using an LED light source is possible. In addition, higher fluorescence reactivity is exhibited compared to coumarin fluorescent substances known in the related arts since one molecule has a plurality of fluorescent substances, and the problem of the coumarin fluorescent substance possibly binding to a binding site of the antigen of the antibody is solved since fluorescence detection is possible even when a minimum number of fluorescent substance molecules bind to an antibody.