To provide a water-based coating composition which is excellent in low-temperature film formation properties and antifreezing properties and can form a coating film excellent in strength and surface nontackiness.

This water-based coating composition does not substantially contain a volatile organic compound and contains, as the binder component, a core/shell emulsion which is obtained by the emulsion polymerization of a polymerizable unsaturated monomer in the presence of water. In the core/shell emulsion, the core is a polymer with a glass transition temperature of -65 to 0°C; the shell is a polymer with a glass transition temperature of 35-120°C and an acid value of 4-80 mgKOH/g; the wt. ratio of the core polymer to the shell polymer is (40/60)-(90/10); and the emulsion particle diameter is 200-2,000nm.