A laser irradiation device and a method of fabricating an organic light emitting display device (OLED) using the same are disclosed. The laser irradiation device includes: a laser source generating a laser beam; a mask disposed below the laser source and patterning the beam and a projection lens disposed below the mask and determining magnification of the laser beam through the mask, wherein the laser beam penetrating the mask has different doses in at least two regions. Thus, the laser irradiation device can maximize emission efficiency and enhance the quality of a transfer layer pattern when an organic layer of the OLED is formed using the laser irradiation device.