The aim of this paper is to discuss the following questions from the viewpoint of Functional Syntax;
(i) What motivates Focus Movement (FM) in Shakespeare's English?
(ii) Why is the landing site of FM restricted to the “edge” of a sentence?
(iii) Why does Shakespeare's English allow much freer FM than Present-day English?
In general, it has been claimed that Rightward FM such as Heavy NP Shift and Extraposition should be triggered by the End-Weight Principle. That is, a heavy or complicated element in a sentenceinitial or middle position is preferably placed at the end position. This explanation based on the information flow, however, encounters serious problems. First, the strict definition of “heaviness” seems unclear. Second, the reason is also obscure why a heavier element should follow a lighter one. Third, the other type of FM, that is, Leftward FM such as Wh-Movement cannot be explained by the above functional principle at all. I will claim that these problems may be solved naturally by a cognitive notion of “balance. ” In short, FM should be motivated in order to keep the most-well balanced structure. The landing site of a moved element should be “edge”because it is the best position to decide the direction of a sentence declination. Finally, it is suggested that the balance-based functional principle should be observed more strictly than some syntactic constraints in Shakespeare's English.