A method, apparatus, and computer program product for performing bidirectional transformation between a first structured document and a second structured document is disclosed. A transformation rule having primitive rules each of which is applicable to respective one of elements specified in units of paths within the first structured document is prepared. A forward transformation is performed, which transforms the first structured document into the second structured document in accordance with the transformation rule. At that time, a transformation record is created. The record contains which primitive rules were applied and which paths were transformed in the forward transformation. The transformed second structured document may be edited by an application-side. After that, a backward transformation is performed, which transforms the second structured document into the first structured document with referral to the transformation record, the transformation rule, and the first structured document.