This paper aims to define the typical syntactic structure of Old Japanese at Man'yôshû. In Old Japanese, two types of alignment exist: the accusative alignment and the active alignment. While the accusative alignment appears in independent clauses which end in the conclusive form (syusi-kei), the active one accompanies subordinate clauses which close in the adnominal form (rentai-kei). I point out that these alignments have a different Case-marking. Furthermore, by focusing on the cartography of syntactic structures in kakari particles, I analyze kakari musubi as a cleft sentence.