  We study the edge states of twisted bilayer graphene and their topological
origin. We show that the twisted bilayer graphene has special edge states
associated with the moir\'{e} pattern, and the emergence of these moir\'{e}
edge states is linked with the sliding Chern number, which describes
topological charge pumping caused by relative interlayer sliding. When one
layer of the twisted bilayer is relatively slid with respect to the other
layer, the edge states are transferred from a single band to another across the
band gap, and the number of the edge states pumped in a sliding cycle is shown
to be equal to the sliding Chern number of the band gap. The relationship can
be viewed as a manifestation of the bulk-edge correspondence inherent in
moir\'{e} bilayer systems.
