  We examine if an efficient particle acceleration takes place by a
magnetic-field-aligned electric field near the light cylinder in a rotating
neutron star magnetosphere. Constructing the electric current density with the
actual motion of collision-less plasmas, we express the rotationally induced,
Goldreich-Julian charge density as a function of position. It is demonstrated
that the 'light cylinder gap', which emits very high energy photons via
curvature process by virtue of a strong magnetic-field-aligned electric field
very close to the light cylinder, will not arise in an actual pulsar
magnetosphere.
