A fluorescent agent accumulation concentration measuring apparatus is configured to include a single-wavelength LED to radiate excitation light to a test bottle loaded in the inside, a barrier filter to transmit only fluorescence from the test bottle, a photoreceptor to receive the fluorescence through the barrier filter and output an electric signal, a detection processing circuit to conduct signal processing of the electric signal from the photoreceptor and detect the fluorescence intensity, and an operation circuit 26 to compare the detection result from the detection processing circuit with an analytical pattern stored in a pattern storage portion and calculate the peak time of the accumulation concentration in a tissue of a sample in the test bottle.