Tooth bleaching gel, that comes in direct contact with the tooth surface for a long time, affects hard dental tissue. Nonthermal plasma consists electrons, ions, charged particles, electric filed and magnetic field. The motion of an electrically charged particle such as electron and ion can generate both electric and magnetic field. This study was conducted to investigate how tooth bleaching with 15 % hydrogen peroxide (HP) and plasma (from electric currents and magnetic fields) affects hard dental tissue. Extracted human teeth were treated with 15 % HP, with and without plasma. We fabricated a 15 % HP gel with neutral pH, and applied the gel and plasma to tooth surfaces for 30 minutes. The overall color change following 15 % HP gel and plasma was higher than in the other groups, and there were no significant changes in microhardness or mineral contents. Application of 15 % HP and plasma showed a bleaching high effect, with no damage to hard dental tissue. Even though 15 % HP has adverse effects, results can be effective without danger if treatment times are kept short.