  We study asymptotical behaviour of resonances for a quantum graph consisting
of a finite internal part and external leads placed into a magnetic field, in
particular, the question whether their number follows the Weyl law. We prove
that the presence of a magnetic field cannot change a non-Weyl asymptotics into
a Weyl one and vice versa. On the other hand, we present examples demonstrating
that for some non-Weyl graphs the ``effective size'' of the graph, and
therefore the resonance asymptotics, can be affected by the magnetic field.
