PURPOSE: To prepare carboxylic acid ester via transesterification using a heterogeneous transition-metal transesterification catalyst having enhanced activity.

CONSTITUTION: Reactants are heated at 50-200°C in the presence of a transition- metal transesterification catalyst on a carrier which is prepared by the following steps; (a) a step to form an oligomer by reacting a transition metal alkoxide of the formula; M(OR)nQm [M is a transition metal: OR is an alkoxy radical: R is a 1-20C alkyl group; (n) is an integer from 2 to a valency of transition metal M; Q is a group having a valency (r) which is not reacted with hydroxyl group of a carrier, alkoxide radical OR or alcohol ROH formed therefrom; (m) is such an integer that n+rm being equal to the valency of transition metal M] with water, and, (b) a step to mix a soln. of the oligomer in an inert solvent with a solid carrier having a surface hydroxyl group.