To provide a rare gas fluorescent lamp allowing thickness irregularity of a phosphor layer to be reduced by improving adhesiveness of a coating film of a phosphor; and to provide a formation method of a phosphor layer excelling in adhesiveness of the phosphor layer to a glass surface and capable of preventing the phosphor layer from being easily separated even when impact or the like is applied.

This rare gas fluorescent lamp is characterized in that a porous base film formed by binding superfine particles each having a particle diameter not greater than 100 nm to one another is formed between an inside surface of an arc tube and the phosphor layer. This formation method of a phosphor layer is characterized by including processes of: preparing a suspension liquid with superfine particles dispersed therein by mixing a mixture solution of a Si alkoxide polymer, superfine particles of insulating powder each having a particle diameter not greater than 100 nm and an organic solvent; forming the porous base film with the superfine particles bound to one another by applying the suspension liquid of the superfine particles to a surface of a glass substrate and drying it; and applying a fluorescent substance to the glass substrate surface with the base film formed thereon by running down a suspension liquid with the fluorescent substance dispersed therein thereto.