It is an object of the present invention to provide a water-based one-pack-type coating composition which can form a coating film having a satisfactory feel of achieving a soft feel and coating film performance simultaneously and further maintains common performance of paint such as excellent design (a matt appearance, etc.), an adhesion property, coating film strength, abrasion resistance, water resistance, oil and grease-contamination resistance. A water-based one-pack-type coating composition of the present invention comprises: an ionomer resin emulsion (A), a polyolefin resin emulsion (B), resin particles (C), and a urethane dispersion (D), wherein a solid content mass ratio (mass ratio as converted into a solid content) of (C)/{(A)+(B)+(D)} is 40/100 to 100/100, a solid content mass ratio of (A)/(B) is 1/3 to 3/1, and a solid content mass ratio of {(A)+(B)}/(D) is 40/60 to 70/30.