Metal-based oxide semiconductors have garnered significant attention as promising materials for solar energy applications. Being composed of metal oxides, oxide semiconductors exhibit superior crystalline stability and lower toxicity compared to organic- and lead-containing perovskite crystals. Additionally, they possess advantageous optical properties, including high light absorption and a band gap width suitable for solar cell applications. Among oxide semiconductors, copper oxides are recognized as one of the most promising materials for p-type semiconductors, with a long history of research. Research and development of solar cells based on copper oxides is accelerating, and some with photovoltaic conversion efficiencies of more than 10% have been fabricated. For solar cells employing oxide semiconductors, sputtering and vacuum deposition methods are primarily utilized. On the other hand, a spin-coating method is widely applied in the fabrication of perovskite solar cells and has attracted attention as a simple and cost-effective thin-film deposition technique, which is necessary for future mass production. Although annealing at high temperatures is commonly used to form thin films of metal oxides, it is also important to reduce the annealing temperature to make this technology widely available. In the present study, copper oxide thin films were fabricated using the spin-coating method, and microstructural analyses were conducted. The successful formation of copper oxide thin films was confirmed, and the microstructures of the thin films were investigated.