Provided is a light source device including: at least one light emitting element of at least one type; at least one far-red phosphor that, when excited by output light from the light emitting element, emits light having a peak in a wavelength range of 680 nm or more to less than 780 nm; and at least one phosphor that, when excited by the output light from the light emitting element, emits light having a peak in a wavelength range different from the wavelength range of the light emitted from the far-red phosphor. The spectrum of light emitted from the light source device has characteristic A below. This light source device has sufficient emission intensity over the entire visible range, i.e., over a wavelength range of from 400 nm to 750 nm inclusive.Characteristic A: The ratio of a minimum emission intensity to a maximum emission intensity in a wavelength range of from 400 nm to 750 nm inclusive is 20% or more.