The present invention addresses the problem of obtaining illumination light having the desired light emission spectrum stably and with simple controls even when using a fluorescent semiconductor light source. A fluorescent semiconductor light source, wherein the green semiconductor light source (36) is configured from an excitation light LED (44) for emitting blue excitation light (LBe) and a green fluorophore (47), which is excited by the blue excitation light (LBe) and emits green fluorescence (LGf). The dichroic filter of the third dichroic mirror (81) of the light path-unifying section (41) has a transmission characteristic such that at least the blue excitation light (LBe) is removed from the light emission spectrum of the mixed light of the blue excitation light (LBe) and the green fluorescence (LGf) emitted by the green semiconductor light source (36) and functions as an excitation light-cutting filter, which cuts the blue excitation light (LBe). The light source device is able to constantly supply illumination light having the desired light emission spectrum without the blue excitation light (LBe) affecting the amount of blue light (LB) from the blue semiconductor light source (35).
