The present invention is an illumination device for tumor detection 1, which improves the visibility of a tumor in which a fluorescent substance is accumulated, and emits excitation light for the fluorescent substance accumulated in the tumor, and the illumination device for tumor detection 1 is provided with: a light emitting diode 7 that emits light of which a wavelength range substantially coincides with an excitation wavelength range for the fluorescent substance； and a blocking part 8 that is provided on a light emission side of the light emitting diode 7, and blocks the same wavelength as at least a part of the excitation wavelength range for the fluorescent substance.
