The present invention discloses a method and apparatus for detecting page boundaries which are capable of accurately detecting complete page boundaries and dealing with many kinds of complex conditions. The method comprises: an edge image detecting step for detecting an edge image from the book document image; a horizontal page boundary detecting step for detecting top page boundaries and bottom page boundaries on the edge image; a binding center line detecting step for detecting the binding center line by searching an intersection point of the left page and the right page on the top page boundaries and the bottom page boundaries; a page width determining step for determining the page width of the book document image; and a vertical page boundary determining step for determining the left page boundary and the right page boundary by using the top page boundaries, the bottom page boundaries, the binding center line and the page width.