  Cosmic rays are hampered by the Moon and a deficit in its direction is
expected (the so-called Moon shadow). The Moon shadow is an important method to
determine the performance of an air shower array. In fact, the westward
displacement of the shadow centre, due to the propagation of cosmic rays in the
geomagnetic field, allows to calibrate the energy scale of the primary
particles observed by the detector. In addition, the shape of the shadow allows
a measurement of the angular resolution and the position of the deficit at high
energy allows the evaluation of the pointing accuracy of the detector. In this
paper we present the observation of the galactic cosmic rays Moon shadowing
effect performed by the ARGO-YBJ experiment in the multi-TeV energy region. The
measured angular resolution as a function of the shower size is compared with
the expectations from a MC simulation.
