A polyvinyl alcohol (PVA)-based airbag base fabric aqueous coating material is described. A blocked polyisocyanate component (B-NCO) and liquid polyol are added to polyvinyl alcohol as a cross-linkage improver and a plasticizer, respectively. The B-NCO is composed of or based on a medium-molecular-weight form as a polyether-modified prepolymer, and used concurrently with a low-molecular-weight form in a small amount. The base fabric coating material is applied on one or both of the sides of a cloth of the base fabric and heated. The acquired coating film is a water-insoluble coat and the coating has excellent heat and moisture resistance (hot water resistance) and flexibility.