Strand with a spiral groove

A strand for an additive manufacturing raw material for a 3D printer and formed in a linear shape, the strand comprising:

• a base material comprising a thermoplastic resin,
• a single fiber bundle formed by bundling fibers, the single fiber bundle continuously extending in an axial direction and being disposed at a center of the base material, wherein
• the fibers of the single fiber bundle are twisted together,
• the thermoplastic resin is impregnated between the fibers,
• an outer periphery of the single fiber bundle is covered with the thermoplastic resin in a circumferential direction,
• the strand comprises a spiral groove portion formed on an outer peripheral surface of the thermoplastic resin along the axial direction,
• the spiral groove portion has a width dimension of 0.001 mm to 10 mm and a depth dimension of 0.001 mm to 10 mm,
• the spiral groove portion includes a predetermined number of spiral groove portions, and
• the number of spiral groove portions is greater than a number of the fiber bundles.