A tool path generation device (20) generates a tool path (L1) for processing hairline-shaped long and narrow grooves (Wa) in the surface (W0) of a workpiece, and is provided with a shape data acquisition unit for acquiring shape data relating to the workpiece, a parameter setting unit (23) for setting shape parameters of hairlines corresponding to the long and narrow grooves (Wa), and a path generation unit (24) for generating the tool path (L1) for processing the hairlines on the basis of the shape data acquired by the data acquisition unit and the shape parameters set by the parameter setting unit (23).