To provide a polypropylene fiber that is stably produced on an industrial scale and has high strength.

The polypropylene fiber comprises a resin composition containing a propylene-based resin (A), and 0.1-14 wt.% of a propylene-based resin (B) containing a propylene-α-olefin copolymer (component (a)) containing 50 wt.% or more of a propylene homopolymer or propylene polymerization unit having an intrinsic viscosity [η] of 0.2-10 dl/g, and an ethylene-α-olefin copolymer (component (b)) containing 50 wt.% or more of an ethylene homopolymer or ethylene polymerization unit having an intrinsic viscosity [η] of 15-100 dl/g in a ratio of 0.01-20 pts.wt. per 100 pts.wt of the component (b), and having an MFR (230°C, 21.2 N) of 0.1-20 g/10 minutes, a melt tension (230°C, 2 mm diameter) of 1.0-50 cN, and a strain hardening property under elongation flow.