To provide a sealing plate for an EL element, and to provide a mother glass substrate for forming multiple sealing plates for the EL element.

The organic EL element 100 comprises: a plate-like transparent substrate 10 made of non-alkali glass and having a passive structure; an organic EL layered product 20 formed on the substrate 10; and this sealing plate 30 formed so as to cover the layered product 20. The sealing plate 30 is fabricated from a plate-like transparent glass material plate made of non-alkali glass by, for instance, wet-etching method, and its center part is machined into a recessed form so as to define a peripheral projection part 31 in its peripheral part. The top part of the projection part 31 is stuck to the substrate 10 by interlaying an adhesive layer 40. The sealing plate 30 has curved parts 35 having a radius of curvature of 300 μm in corner parts 34 of the recessed part 32.