The present invention makes the insertion perception during actual surgery to be equivalent to the insertion perception of a catheter into a blood vessel model when water is used as the circulating fluid. A lubricant regulating fluid primarily composed of water is mixed with an aqueous metal salt and a surfactant as a lubricant regulating agent of the lubricant regulating fluid. A cationic surfactant, an anionic surfactant, a nonionic surfactant, or a dipolar ionic surfactant may be used as the surfactant. Also, the metal salt may be an alkaline metal salt, an alkaline earth metal salt, an aluminum salt, a ferric salt, or the like. In an example, the lubricant regulating fluid obtained by mixing an aqueous metal salt with water is prepared, and the lubrication and non-adherent properties of a catheter into a simulated blood vessel model are improved.
