As increase of beam power, beam instruments play an essential role in the Hadron accelerator facility. In J-PARC, the pitting erosion on the mercury target vessel for the spallation neutron source is one of a pivotal issue to operate with the high power of the beam operation. Since the erosion is proportional to the 4th power of the beam current density, the minimization of the peak current density is required. To achieve low current density, the beam-flattening system by nonlinear beam optics using octupole magnets in J-PARC. By the present system, the peak density was successfully reduced by 30% compared to the ordinary linear optics. Also in J-PARC, transmutation experimental facility is planned for the realization of the accelerator-driven system (ADS), which will employ powerful accelerator with the beam power of 30 MW. To achieve equivalent damage on the target as the ADS, the target will be received high current density. For the continuous observation of the beam status on the target, a robust beam profile monitor is required. We have been developed beam profile monitor by using heavy-ion of Ar beam to give the damage efficiently.