The purpose of the invention is to provide a film formation apparatus capable of forming an EL layer with a high purity and a high density, and a cleaning method. The invention is a formation of an EL layer with a high density by heating a substrate 10 by a heating means for heating a substrate, decreasing the pressure of a film formation chamber with a pressure decreasing means (a vacuum pump such as a turbo-molecular pump, a dry pump, or a cryopump) connected to the film formation chamber to 5.times.10.sup.-3 Torr (0.665 Pa) or lower, preferably 1.times.10.sup.-3 Torr (0.133 Pa) or lower, and carrying out film formation by depositing organic compound materials from deposition sources. In the film formation chamber, cleaning of deposition masks is carried out by plasma.