To realize the heightening of curing efficiency and electric efficiency and the reduction in the size and weight of the irradiator by collecting necessary wavelength energy in a light irradiator for a curing agent that radiates ultraviolet rays and short-wavelength visible rays.

The light irradiator for a curing agent is provided with a metal halide lamp 3 provided in a lighting body 1, a lens 5 fixed to a front frame 4 in the front of the lamp 3, a starter 6 and an electric source apparatus 7 disposed in the lighting body 1 in the rear of the lamp 3, and a cooling fan 8 disposed in the body 1. Output light is devoid of ultraviolet rays of a wavelength of 280 nm or shorter, and ultraviolet rays having wavelengths of 280-600 nm and visible rays occupy 50% of the total emission energy.