There is provided a water-based resin composition that contains a polymer (A) containing, as essential raw materials, a hydrogenated polybutadiene (a1) with an iodine value in the range of 5 to 25, a monomer (a2) with an acid group, and a monomer (a3) with a hydroxy group, a basic compound (B), and an aqueous medium (C), wherein the hydrogenated polybutadiene (a1) constitutes 4% to 38% by mass of the raw materials of the polymer (A), and the polymer (A) has an acid value in the range of 10 to 65 mgKOH/g. A water-based resin composition of the present invention has high storage stability and forms a coating film with good physical properties, such as high adhesiveness to various substrates and high blocking resistance, and is therefore suitably used in a water-based paint.