Provided are a metal chalcogenide thin film and a method and device for manufacturing the same. The metal chalcogenide thin film includes a transition metal element and a chalcogen element, and at least one of the transition metal element and the chalcogen element having a composition gradient along the surface of the metal chalcogenide thin film, the composition gradient being an in-plane composition gradient. The metal chalcogenide thin film may be prepared by using a manufacturing method including providing a transition metal precursor and a chalcogen precursor on a substrate by using a confined reaction space in such a manner that at least one of the transition metal precursor and the chalcogen precursor forms a concentration gradient according to a position on the surface of the substrate; and heat-treating the substrate.