In natural languages, the mapping from surface form to meaning is often quite complex, and hence the acquisition of the phenomena at the boundary between syntax and semantics has been one of the central issues in current acquisition research. This study addresses the issue of whether children have adult-like knowledge of LF "wh"-movement and its locality constraints. The results of my experiment demonstrate that knowledge of these properties is already in the grammar of Japanese-speaking preschool children. These results corroborate the findings of previous acquisition research on overt "wh"-movement that even preschool children conform to locality conditions on movement. This finding supports the continuity hypothesis (e.g., Crain & Thornton 1998) from a new perspective, in that the relevant movement occurs in the LF component and hence is invisible in the input children receive. (Contains 10 footnotes.)