Artificial hair fiber

A fiber for artificial hair using a polyvinyl chloride-based resin composition, wherein

• the polyvinyl chloride-based resin composition comprises 90-99 parts by mass of a polyvinyl chloride-based resin (A) having a viscosity-average polymerization degree of 450-1,450 and 1-10 parts by mass of a crosslinked vinyl chloride-based resin (B) having a viscosity-average polymerization degree for a component that is soluble in tetrahydrofuran of 1,900-2,300,
• the difference between the viscosity-average polymerization degree of the polyvinyl chloride-based resin (A) and the viscosity-average polymerization degree for the component that is soluble in tetrahydrofuran of the crosslinked vinyl chloride-based resin (B) is 600-1,850, and,
• the cross-sectional shape of the fiber for artificial hair has a first projection, a second projection, and a third projection extending outward from a center C of the cross-sectional shape and when the length of the first projection from the center C is set as L1, wherein L1 is 65-80 μm, the length of the second projection from the center C is set as L2, and the length of the third projection from the center C is set as L3, the shapes of the projections satisfy (2) and (3) below:
• (2) the ratio of a width W1 (0.15) of the first projection at a distance of 0.15L1 from the center C and a width W1(0.9) of the first projection at a distance of 0.9L1 from the center C (W1(0.15)/W1(0.9)) is 1.5-2.3;
• (3) the ratio of a width W2(0.15) of the second projection at a distance of 0.15L2 from the center C and a width W2(0.9) of the second projection at a distance of 0.9L2 from the center C (W2(0.15)/W2(0.9)) is 2.0-2.2;
• and the ratio of a width W3(0.15) of the third projection at a distance of 0.15L3 from the center C and a width W3(0.9) of the third projection at a distance of 0.9L3 from the center C (W3(0.15)/W3(0.9)) is 1.9-2.4,
• and wherein the length L1 of the first projection, length L2 of the second projection, and the length L3 of the third projection from the center C satisfy L3≤L2, 0.8L1≤L2≤0.95L1 and 0.8L1≤L3≤0.95L1.