Zinc-based plated steel sheet having post-treated coating formed thereon

A zinc-based plated steel sheet having a post-treatment coating, the zinc-based plated steel sheet comprising:

• a steel sheet;
• a zinc-based plating layer formed on the steel sheet;
• and
• a post-treatment coating formed on the zinc-based plating layer, wherein the post-treatment coating includes a coating upper portion and a coating lower portion, a thickness of the coating lower portion being ¼ to ¾ of a total thickness of the post-treatment coating,
• wherein the post-treatment coating includes a metal oxide salt and an organic compound, the metal oxide salt including at least one metal selected from the group consisting of molybdenum (Mo), titanium (Ti), and zirconium (Zr), and
• wherein an atomic ratio (O/M) of oxygen (O) to metal (M) derived from a metal oxide salt included in the post-treatment coating is greater than 2 and smaller than 20,
• an atomic ratio (O/M) of oxygen and metal derived from a metal oxide salt of the coating upper portion is greater than 3.2, and
• an atomic ratio (O/M) of oxygen and metal derived from a metal oxide salt of the coating lower portion is less than 5.