  The detection of gravitational waves and electromagnetic counterparts from a
binary neutron star (BNS) merger confirmed that it is accompanied by the launch
of fast merger ejecta. Analogous to supernova remnants, forward shocks formed
by the interaction of the ejecta with interstellar material will produce
high-energy cosmic rays. We investigate the possibility that Galactic neutron
star merger remnants (NSMRs) significantly contribute to the observed cosmic
rays in the energy range between the knee and the ankle. Using typical
parameters obtained by modeling of GW170817, we find that NSMRs can accelerate
iron nuclei up to $\sim500$ PeV. We calculate the cosmic-ray spectrum and
composition observed on Earth, and show that the Galactic NSMR scenario can
account for the experimental cosmic-ray data in the 20 -- 1000 PeV range. Our
model can naturally explain the hardening feature around 20 PeV for total
cosmic-ray spectrum, which has been observed by the Telescope Array Low Energy
extension and the IceTop air shower array.
