Readily-fibrillable fibers of PVA polymer, having good chemical resistance, hydrophilicity, weather resistance and water resistance have a flattened cross-sectional profile and have a mean thickness D (μm) that satisfies the following formula (1):0.4≦D≦5 (1)wherein D=S/L; S indicates the cross-section area (μm2) of the fibers; and L indicates the length (μm) of the major side of the cross section of the fibers. The fibers can be used for making nonwoven fabrics.