We report the fabrication of atomically abrupt interfaces of titanium dihydride (δ-TiH2) films and α-Al2O3(001) substrates. With the assistance from reactive hydrogen in plasma, single-phase δ-TiH2 epitaxial thin films were grown on α-Al2O3(001) substrates using the reactive magnetron sputtering technique. Scanning transmission electron microscopy measurements revealed an atomically abrupt interface at the δ-TiH2(111) film and Al2O3(001) substrate. These results indicate that the reactive magnetron sputtering has great potential to deposit various epitaxial thin films of hydrides restricted by the hydrogenation limit. The fabrication of high-quality hydride epitaxial thin films with atomically controlled interfaces paves the way for future hydride electronics.