Manufacturing process of element chip

A manufacturing process of an element chip comprises steps of preparing a substrate including a plurality of etching regions and element regions each containing a plurality of convex and concave portions, holding the substrate and a frame with a holding sheet, forming a protective film by applying a first mixture to form a coated film above the substrate and by drying the coated film to form the protective film along the convex and concave portions, the first mixture containing a water-soluble first resin, water and a water-soluble organic solvent and has a vapor pressure higher than water, removing the protective film by irradiating a laser beam thereon to expose the substrate in the etching regions, plasma-etching the substrate along the etching regions while maintaining the protective film in the element regions to individualize the substrate, and removing the protective film by contacting the protective film with an aqueous rinse solution.