  We theoretically investigate the vortex spin Hall effect, i.e., a novel spin
Hall effect driven by the motion of superconducting vortices, by focusing on
the role of superconducting fluctuations. Within the BCS-Gor'kov microscopic
approach combined with the Kubo formula, we find a strong similarity between
the vortex spin Hall effect and the vortex Nernst/Ettingshausen effect.
Calculated temperature dependence of the voltage signal due to the inverse
vortex spin Hall effect exhibits a strong enhancement by vortex fluctuations.
This result not only provides a possible explanation for a prominent peak found
in the spin Seebeck effect in a NbN/Y$_3$Fe$_5$O$_{12}$ system, but also leads
to a proposal of new experiments using other superconductors with strong
fluctuations, such as cuprate or iron-based superconductors.
