Chemical conversion agent

The purpose of the present invention is to provide a chemical conversion agent which forms a chemical conversion coating film in the surface or on the surface of a metal material, and which has excellent appearance after chemical conversion and excellent corrosion resistance that is evaluated by a VDA 621-415 method or an exposure test after coating, and is able to be used in a wide temperature range. The purpose is achieved by a chemical conversion agent which forms a chemical conversion coating film in the surface or on the surface of a metal material, and which contains a supply source of fluorine ions, a supply source A of ions containing zirconium, a supply source B of ions containing aluminum, and a water-soluble or water-dispersible polymer C containing 90% by mole or more of a structural unit represented by formula (i) or a salt C of the polymer, while satisfying formula (1). Formula (1): (Ac + Bc) * (pH - 3)X ≥ 0.38 In the formula, X = 7.2 * 12(-1.6 * (Ac + Bc)).