  Pulsar wind nebulae (PWNe) are main gamma-ray emitters in the Galactic plane.
Although the leptonic scenario is able to explain most PWNe emission well, a
hadronic contribution cannot be excluded. High-energy emission raises the
possibility that gamma-rays are hadronically produced which inevitably leads to
the production of neutrinos. We report a stacking analysis to search for
neutrino emission from 35 PWNe that are very-high-energy gamma-ray emitters and
the results using 9.5 years of all-sky IceCube data. In the absence of any
significant correlation, we set upper limits on the total neutrino emission
from those PWNe and constraints on the hadronic component.
