A light irradiation apparatus 10 is configured to comprise: a supporting means 11 for supporting a semiconductor wafer W as an irradiated object, the semiconductor wafer W being stuck with an adhesive sheet S having an ultraviolet curable adhesive on a circuit formation surface； and a light irradiating means 13 having a focus axis P at a location spaced by a predetermined distance, and being provided so as to enable head-swinging motion thereof. The supporting means 11 is supported by a multi-joint robot 12, and relatively displaces the wafer W so as to prevent an adhesive layer surface SA of the adhesive sheet S from deviating from a position of the focus axis P, when the ultraviolet ray irradiating means 13 performs the head-swinging motion.
