The BCI (brain-computer interface) systems have been realized by instructing the users to execute the specific tasks, e.g. the motor imagery or the selective attention of the specific target sensory stimuli. Such tasks which the users should do to use BCI are different from the effect of the BCI system. In other words, there is a "meta-task" between the user's task and the effect of BCI control. For more easy-to-use BCI system to control external devices in more straightforward way, such divergences between the effect and the task should be reduced. In this article, our basic studies of the EEG-based BCI to achieve the direct control by user's will are introduced and discussed.