An inkjet printing apparatus, method of printing ink using the same and method of fabricating display device are provided. The method of printing ink includes: ejecting ink in which a plurality of particles is dispersed from an inkjet head; irradiating the ejected ink with a first light and a second light having different wavelengths to acquire data on a first exit light and a second exit light emitted from the ink; calculating a concentration of the particles in the ink from the data on the first exit light and the second exit light; and checking whether the concentration is out of an error range from a reference value, where the first light has a wavelength of about 500 nm or less, and the second light has a wavelength of about 1000 nm or more.