Altermagnetism has been widely explored in 3D and 2D crystals, but its one-dimensional realization remains largely unexplored. Here we propose an altermagnetic nanotube formed by rolling a 2D altermagnet, which converts blacksymmetry-enforced directional spin anisotropy in momentum space into blackspin–chirality locking in the screw-symmetric geometry. Unlike curvature-induced magnetization in bent films, blackthe nanotube remains compensated and produces no net magnetization. Two reciprocal effects emerge: (i) blackspin-selective injection drives a helical current whose handedness is fixed by the spin, yielding opposite-sign axial magnetic fields; and (ii) a time-varying axial flux generates a circumferential Faraday field that drives blackequal and opposite axial charge currents in the two fixed spin channels, yielding a charge-neutral spin-channel current in the open-circuit weak-SOC limit. black{Explicit the first-principles calculations of the relaxed V₂Se₂O nanotube reveal spin-resolved helical |ψ|² modulations near both band edges, while a parent-monolayer Wannier–Boltzmann calculation quantifies the energy-dependent spin-odd transverse response and corresponding ideal thin-wall field scale.