<p>A cathode ray tube has an insulating layer formed at at least a part of the outer surface of a neck tube. The insulating layer is a layer obtained by coating and baking a sol prepared by dispersing one or two or more metal alkoxides and metal salts in a hydrophilic oligomer state by adding water and an acid to a solution having one or two or more metal alkoxides and metal salts dissolved in an organic solvent such as an alcohol.</p>
