A method for manufacturing light emitting devices is provided. The method may reduce the inner pressure of a laminated image emitting device panel, thereby preventing failure of the panel. The method includes holding a first substrate with a lower chuck located in a vacuum chamber; holding a second substrate with an upper chuck located opposite the first chuck in the vacuum chamber; creating a high vacuum in the vacuum chamber; correcting positions of the first substrate and the second substrate; supplying gas having a temperature of about 50 to about 200° C. into the vacuum chamber; temporarily laminating the first substrate and the second substrate; venting the vacuum chamber; and bonding the first substrate and the second substrate. The panel is laminated after being filled with a heated gas and thus, when it is exposed to room temperature, the mobility of the gas decreases while reducing its initial inner pressure, thereby preventing panel failure.