  Particle acceleration during the magnetorotational instability (MRI) in a
collisionless accretion disk was investigated by using a particle-in-cell (PIC)
simulation. We discuss the important role that magnetic reconnection plays not
only on the saturation of MRI but also on the relativistic particle generation.
The plasma pressure anisotropy of $p_{\perp} > p_{\para}$ induced by the action
of MRI dynamo leads to rapid growth in magnetic reconnection, resulting in the
fast generation of nonthermal particles with a hard power-law spectrum. This
efficient particle acceleration mechanism involved in a collisionless accretion
disk may be a possible model to explain the origin of high energy particles
observed around massive black holes.
