  It has been recognized that magnetic reconnection process is of great
importance in high-energy astrophysics. We develop a new two-dimensional
relativistic resistive magnetohydrodynamic (R$^2$MHD) code, and carry out
numerical simulations of magnetic reconnection. We find that outflow velocity
reaches Alfv\'{e}n velocity in the inflow region, and that higher Alfv\'{e}n
velocity provides higher reconnection rate. We also find Lorentz contraction
plays an important role in enhancement of reconnection rate.
