A method of producing a medical instrument whereby a highly hydrophilic and lubricant coating layer having a high durability can be formed by a simple technique and thus highly hydrophilic and lubricant properties can be imparted to a surface of a medical instrument. An intraocular lens insertion instrument having been subjected to a surface treatment as described above is also provided. The method comprises the steps of: preparing a coating solution by mixing at least a water-insoluble polymer having carboxyl group and a polyfunctional reactive compound with an organic solvent; applying this solution on the surface of the medical instrument; conducting crosslinking; and performing a chemical reaction process whereby the coating layer is made hydrophilic. The intraocular lens insertion instrument is made hydrophilic by forming the coating layer as described above on an inner surface of an insertion tube portion, crosslinking and then performing the chemical reaction process.