Chemical conversion treatment solution and chemically converted steel sheet

A chemical treatment solution for coating a zinc-based plated steel sheet having a zinc-based plating layer containing 0.1 to 22.0 mass % of aluminum, the chemical treatment solution comprising:

• a water-soluble molybdate;
• a vanadium salt;
• an amine;
• a group 4A metal oxoate;
• and
• a phosphate compound,
• wherein:
• a molar ratio of molybdenum to vanadium in the chemical treatment solution is 0.4 to 5.5,
• a molar ratio of the amine to the vanadium in the chemical treatment solution is 0.3 or more,
• a content of a hydrophilic resin in the chemical treatment solution is at most 100 mass % based on a total amount of the vanadium and the molybdenum in the chemical treatment solution,
• a total content of fluorine derived from a fluorine ion or a fluorometal ion in the chemical treatment solution is at most 30 mass % based on the total amount of the vanadium and the molybdenum in the chemical treatment solution, and
• a content of silicon derived from a silanol group in the chemical treatment solution is at most 50 mass % based on the total amount of the vanadium and the molybdenum in the chemical treatment solution.