PURPOSE: To enable provision of a great peak illuminance by drawing in air for cooling the lamp while supplying the lamp with a high electric input to produce high light-intensity radiation and by irradiating a work placed at the second focal point of an elliptic mirror with light having a great peak intensity.

CONSTITUTION: A illuminator comprises a mirror 2 having the shape of bucket with an elliptical cross section or the shape of an elliptical cylinder, a bar-like lamp 1 arranged so that the center of the lamp 1 coincides with the first focal point of the ellipse formed by the mirror 2, and a lamp housing 3 that houses the lamp 1 and the mirror 2 and has an opening for illumination. The lamp 1 is has a reduced pipe diameter. The mirror 2 has an opening formed in its top portion. A cooling nozzle 4 extends through the opening so that the cooling air suction opening 4a is a predetermined distance apart from the lamp 1. While air is drawn in through the cooling air suction opening 4a of the nozzle 4 in order to cool the lamp 1, the lamp 1 is supplied with high electric input to radiate light with high intensity, so that a work placed at the second focal point of the ellipse of the mirror 2 is irradiated with light having a great peak intensity.