Agri-food garlic has been recognized as healthful because of its antibacterial, anticancer and antioxidant effects. As such, its consumption is steadily increasing. This study was conducted to amplify the healthful ingredient of garlic, allicin, using light irradiation. The following conclusions were drawn from the investigation of peeled garlic under various conditions like fluorescent lighting, color (green, yellow, blue and red) and ultraviolet light (UV-A, UV-B and UV-C). The allicin content increased most with the 15-second 0.129 W/m2 (40 W) UV-B treatment of the garlic at a 700 mm distance from the light source. At the treatment of the garlic with 126 lx (40W) red light for 24 hours at a 700 mm distance from the light source, its allicin content increased from 15.15±0.25 mg/g to 15.15±0.34 mg/g, for a 10-percent amplification effect. Therefore, it is believed that the healthfulness of garlic can be amplified through irradiation processing of its healthful ingredient, allicin, and the development of its processing unit.