This paper reports a novel micromachined corona-based unipolar aerosol charger for improving particle charging efficiency. The particle charging efficiency is an important parameter in aerosol measurement. The low charging efficiency of the previous tip-to-plate corona charger due to charged particle losses led to difficulty in aerosol measurement. The proposed corona charger could reduce the electrical losses of charged particles by separating ionization and charging zones. The electrical losses of charged particles and particle charging efficiency were experimentally examined. At the result, the charging performance of proposed corona charger was 3 times higher than that of the previous tip-to-plate corona charger.