A method for using a film formation apparatus for a semiconductor process to form a thin film on a target substrate while supplying a film formation reactive gas from a first nozzle inside a reaction chamber includes performing a cleaning process to remove a by-product film deposited inside the reaction chamber and the first nozzle, in a state where the reaction chamber does not accommodate the target substrate. The cleaning process includes, in order, an etching step of supplying a cleaning reactive gas for etching the by-product film into the reaction chamber, and activating the cleaning reactive gas, thereby etching the by-product film, and an exhaust step of stopping supply of the cleaning reactive gas and exhausting gas from inside the reaction chamber. The etching step is arranged to use conditions that cause the cleaning reactive gas supplied in the reaction chamber to flow into the first nozzle.