<p>A method by which a polystannoxane compound which has a specific structure and is useful as a transesterification catalyst having excellent catalytic activity can be recovered at a satisfactory recovery percentage without deactivating the catalyst. A polystannoxane represented by the following general formula 1: 1 wherein R represents methyl or ethyl X's each independently represents an electron-attracting group having lone pair electrons on the atom bonded to the tin atom and n is an integer of 1 to 8 is used as a transesterification catalyst to cause an alcohol and a carboxylic ester to undergo transesterification. Thereafter, the polystannoxane is extracted with water from the resultant crude reaction product to thereby recover the polystannoxane.</p>
