A illumination device comprises an excitation light source, a first fluorescent material that converts the wavelength of light emitted from the excitation light source and emits light having a light emission peak wavelength in a range of 780 nm or more and 1,600 nm or less, and a cut filter that blocks light in a wavelength range of 870 nm or less, wherein the first fluorescent material contains a fluorescent material having a composition of rare earth aluminate containing Ce and Nd.