The intentional electromagnetic interference (IEMI) injection method using sinusoidal waves cannot be protected with conventional countermeasures proposed and expanded the range of target devices. Therefore, evaluating devices against side-channel attacks is more important than in the past. A control in the phase of sinusoidal waves used in this attack can affect the extraction of secret keys. Nevertheless, there was not enough discussion about the effects of the controlled phase in conventional studies. We considered the effect of control in the phase of sinusoidal waves and proposed the new evaluation method based on this consideration. This method makes it possible to evaluate the devices taking into account the effects of controlled phases that have not been considered before. This method was devised based on the idea that evaluation is performed while changing the phase of sinusoidal waves. We experimented using actual cryptographic hardware to substantiate the effect of changing the phase of the sinusoidal wave on the attack and verify the validity of the proposed method. We confirmed that the phase of sinusoidal waves affects the attack as expected and showed that the proposed method is more suitable for evaluation than the conventional method. We also pointed out the problems of the proposed method and indicated the point of possible further improvement.