PURPOSE: To produce the titled polymer which can be readily purified and contains no impurity, by reacting a cyclodextrin having a MW increased to such an extent that it does not become insoluble with a crosslinking agent to form an insoluble polymer.

CONSTITUTION: A cyclodextrin having a MW increased to such an extent that it does not become insoluble and an average MW of 5,000W8,000 is obtained by adding 0.3W1.0pt.wt. NaOH, 1W2pts.wt. water, 0.1W1.0wt% sodium borohydride and 0.1W1.0pt.wt. crosslinking agent (e.g., epichlorohydrin) to 1pt.wt. cyclodextrin, reacting the mixture at 30W80°C for 0.5W2hr under agitation at 100W500rpm. 5W100pts.wt. crosslinking agent is added to 1pt.wt. cyclodextrin and the mixture is reacted at 30W80°C for 0.5W2hr under agitation at 500W3,000rpm to obtain an insoluble polymer.