This paper proposes analysis a dead-time error voltage compensation method with a disturbance observer for vector control, and analyses the proposed method. The dead-time compensation is very important to improve performances in the low speed region. The proposed compensation method is composed in the d-q rotational frame with the disturbance observer. As a result, a disturbance transmission characteristic becomes same as a high-pass filter. Then a stability of the proposed controller is hardly affected by controller parameters. In this paper, the validity of analysis is confirmed by experimental results under some conditions. The experimental results are similar to analyzed characteristics and indicate a validity of the analysis results.