A method for producing plasticizers which contain titanium in only a very small amount is provided. According to this method, the amount of waste water is very small. This method comprises reacting phthalic anhydride with an alcohol having 4-18 carbon atoms in the presence of, as a catalyst, a tetraalkyl titanate or a polymer thereof, and has a feature in the treatment of the resultant ester with a solid alkali and adsorbing agent(s) in the absence of water.