In hybrid electric vehicle (HEV) and electric vehicle (EV), some high-frequency electrical devices such as traction motors, generators, air conditioner motors, and reactors are used. Nonoriented electrical steel sheets are used as the core material for such electrical devices, and they are contributing to the improvement in the efficiency of the apparatus. Electrical steel sheets for energy-efficient motors are suitable for HEV/EV traction motors. The developed material achieved low iron loss and high magnetic flux density by high purification and texture control. Thin-gauge electrical steel sheets for high-frequency motors show lower iron loss than that of conventional products in high-frequency range. A 6.5% Si steel sheet shows zero magnetostriction and low iron loss in the 400 Hz to 10 kHz, so it is the optimum material for low noise high-frequency reactors. A Si gradient steel sheet, which has gradient distribution of Si throughout sheet thickness with higher concentration of Si at the surface layer of the steel sheet shows lower iron loss than the 6.5% Si steel sheet in the high-frequency range from 5 kHz to 100 kHz. This chapter reviews the features and applications of these nonoriented electrical steel sheets.