An indoor light source emits light having an emission spectrum including a first peak in a wavelength region of 440 to 460 nm, a second peak in a wavelength region of 540 to 560 nm, and a third peak in a wavelength region of 610 to 630 nm. When the highest one of intensities at the first peak, the second peak, and the third peak is 1 in terms of relative intensity, the emission spectrum includes a lowest light intensity of 0.7 or higher in terms of relative intensity in λ1 to λ2 in nm, and a lowest light intensity of 0.8 or higher in terms of relative intensity in λ2 to λ3 in nm, where λ1 is a peak wavelength at the first peak in nm, λ2 is a peak wavelength at the second peak in nm, and λ3 is a peak wavelength at the third peak in nm.