The acquisition of word order has been one of the central issues in the study of child language. One striking finding from the detailed investigation of various child languages is that from the earliest observable stages, children are highly sensitive to the basic word order of their target language. However, the evidence so far comes mainly from the acquisition of rigid word-order languages. In light of this background, this study presents new evidence that such early sensitivity to basic word order can be observed even in the acquisition of Japanese, a free word-order language. (Contains 3 tables and 9 footnotes.)