PROBLEM TO BE SOLVED: To provide an illumination device for plant cultivation using artificial light, which can efficiently irradiate leaves at a lower section of the plant even when applying high intensity light.SOLUTION: The illumination device for plant cultivation includes: a main light source which emits monochromatic light or mixed-colored light of which wavelengths are between 400 nm or more and 700 nm or less and photosynthesis photon flux density is at 200 μmol/m/s or greater; and a far-infrared light source which emits far-infrared light. The main light source and the far-infrared light source include semiconductor light-emitting elements.