A surface EMG signal is one of the most widely used signals as input signals for wearable robots. However, EMG signals are not always available to all users. On the other hand, an EEG signal has drawn attention as input signals for those robots in recent years. However, the EEG signal does not have straightforward relationships with the corresponding brain part. Therefore, it is more difficult to find the required signals for the control of the robot in accordance with the user's motion intention using the EEG signals compared with that using the EMG signals. In this paper, both the EMG and EEG signals are used to estimate the user's motion intention. The EMG signals are used as main input signals because the EMG signals have higher relative to the motion of a user. The EEG signals are used as sub signals in order to cover the estimation of the user's motion intention when all required EMG signals cannot be measured. The effectiveness of the proposed method has been evaluated by performing experiments.