A cleaning method of removing a vapor-deposition material adhering to equipments without exposure to the atmosphere is provided. A vapor-deposition material adhering to equipments (components of a film-forming apparatus) such as a substrate holder, a vapor-deposition mask, a mask holder, or an adhesion preventing shield provided in a film-forming chamber are subjected to heat treatment. Because of this, the adhering vapor-deposition material is re-sublimated, and removed by exhaust through a vacuum pump. By including such a cleaning method in the steps of manufacturing an electro-optical device, the manufacturing steps are shortened, and an electro-optical device with high reliability can be realized.