Copper-basedhigh-temperature superconductors share acommon featurein their crystal structure, which is the presence of a CuO2 plane, where superconductivity takes place. Therefore, importantquestions arise as to whether superconductivity can exist in a singlelayer of the CuO2 plane and, if so, how such superconductivityin a single CuO2 plane differs from that in a bulk cupratesystem. To answer these questions, studies of the superconductivityin cuprate monolayers are necessary. In this study, we constructeda heterostructure system with a La2-x Sr x CuO4 (LSCO) monolayercontaining a single CuO2 plane and measured the resultingelectronic structures. Monolayer LSCO has metallic and bulk-like electronicstructures. The hole doping ratio of the monolayer LSCO is found todepend on the underlying buffer layer due to the interface effect.Our work will provide a platform for research into ideal two-dimensionalcuprate systems.