A glass substrate of a display panel onto which an organic electroluminescence (EL) element or the like is formed is sealed by affixing the glass substrate and a sealing member such as a sealing glass onto which an adhesive has been applied. During this process, the temperature of the adhesive is controlled by, for example, controlling the temperature of the nitrogen gas to fill a chamber through a temperature adjusting device, so that the viscosity of the adhesive is adjusted. In this manner, quick and precise sealing of the display substrate by the sealing member and the adhesive can be achieved.