Provided is a method for preparing an organic electronic device, comprising steps of: applying an ink composition on a substrate, on which an organic electronic element is formed; applying heat thereto before curing the applied ink composition; and curing the applied ink composition by irradiating with light having a wavelength in a range of 300 nm to 450 nm. Also provided is an organic electronic device, comprising a substrate, an organic electronic element formed on the substrate, and an organic layer sealing the entire surface of the organic electronic element, wherein after the organic layer is maintained at 110° C. for 30 minutes, the out-gas amount measured using Purge & Trap-gas chromatography/mass spectrometry is less than 150 ppm.