Hairdryers can emit metallic ultrafine particles (UFPs) while using in the hot mode, which can cause adverse health effects. In this study, 5 domestic hairdryers were tested in a chamber. 3 of the hairdryers were made with brushed motors, while others had brushless DC motor (BLDC). The UFP emission characteristics of those hairdryers were measured and compared in the hot and cool modes. The brushed DC motors emitted nucleation mode particles produced by evaporation and condensation of metals from the surfaces of heating coils and sparks between brushes and commutators in the motors smaller than 20 nm while using the hairdryers. The UFPs were grown up to 200 nm in the chamber during the tests in 30 min. The emission rates (ERs) for the brushed DC motor used hairdryers were in the range of 9.45×109~1.81×1011 #/min. The ERs were between those for the indoor usages of laserprinter and smoking, which can influence on the health of users. However, 2 BLDC hairdryers showed >100 times less ERs than those with brushed DC motors, which helps to maintain good indoor air quality.