  In this note, we treat a pair of a K3 surface and a non-symplectic
automorphism of order 7m (m=1, 3 and 6) on it. We show that if the fixed locus
of a non-symplectic automorphism order 7 is "special" then the pair is unique
up to isomorphism. And we describe fixed loci of non-symplectic automorphisms
of order 21 and 42.
