In a core/sheath type temperature-sensitive shape-transformable composite filament comprising a thermoplastic resin (A) and a thermoplastic polymer (B) having a glass transition temperature within the range of from 0 DEG C to 70 DEG C, the composite filament is constituted in proportions satisfying the following expressions (1), (2) and (3). In the core; <MATH> In the sheath; <MATH> <MATH> The filament is useful as doll hair the hair style of which is thermally shape-transformable to any desired shapes even by infants, and is easily fixable to the transformed shape by cooling.
Core/sheath type temperature-sensitive shape-transformable composite filaments