Magnetic materials instantly respond to changes in external magnetic fields by altering their internal magnetic domains. Even when subjected to alternating magnetic fields of tens of kHz or hundreds of kHz, the magnetic domains change accordingly. Recently, when using pulse-width modulation (PWM) inverter excitation, undesirable phenomena such as overshoot and ringing occur between the inverter and the motor. In inverters using IGBT devices, overshoot and ringing occur in the range of several hundred nanoseconds, while in inverters using Silicon carbide (SiC) or Gallium nitride (GaN) devices, these phenomena occur within several tens of nanoseconds. The problem is that it is extremely difficult to verify how much these phenomena affect equipment such as motors. This is because there is no established technology for accurately measuring them. When measuring magnetic properties during inverter operation, it is important to be aware that there are many sources of noise. Various countermeasures are necessary to minimize the noise as much as possible. To mitigate these noise issues, it is necessary to use isolation digitizers or differential amplifiers and differential probes, minimize the length of wiring where common-mode noise is conducted, and ensure the oscilloscope’s power supply is used through an isolation transformer. Compared with sine wave excitation, the increase factor of the iron loss by inverter magnetization was clarified using the magnetic hysteresis curve and change of the parameter which can be understood intuitively was explained. When α (rate of hysteresis curve between the inverter excitation and the sine wave excitation), β (width of the closed loop using inverter excitation around 0 T), and the open loop using the inverter excitation around 0.8 T are increased by the switching operation of the inverter excitation, they increase the area of the hysteresis curve and makes iron loss increase compared with the sine wave excitation. On the other hand, the increase factor of the iron loss by the inverter excitation was clarified, and explanation which can be understood intuitively was given. The low modulation factor, the low career frequency, and the high VDC of the inverter are made to increase the factors such as α and β and increase the area of the magnetic hysteresis curves and they cause of the iron loss increment. Furthermore, α and β are made to fluctuate by the control method of the motor drive using the inverter. That is, the change of the inverter parameters fluctuates the iron loss due to a trade-off.