▎ 摘　　要

We investigate the quantum Hall effect (QHE) in a graphene sample with Hall-bar geometry close to the Dirac point at high magnetic fields up to 28 T. We have discovered a plateau-insulator quantum phase transition passing from the last plateau for the integer QHE in graphene to an insulator regime nu = -2 -> nu = 0. The analysis of the temperature dependence of the longitudinal resistance gives a value for the critical exponent associated with the transition equal to kappa = 0.58 +/- 0.03.