The present invention provides a biological mucous membrane model having high reproducibility of the evaluation result of the retention that is obtained in a case where a mucous membrane protective agent is applied to the mucous membrane of the living body, in a case where the mucous membrane protective agent such as an oral mucous membrane protective agent is applied; and a method of evaluating retention of a mucous membrane protective agent. The biological mucous membrane model according to the embodiment of the present invention has a hydrogel layer, a lipid-containing layer containing a lipid, which is disposed on the hydrogel layer and has through-holes along in a thickness direction, and a hydrophilic polymer layer disposed on the lipid-containing layer in this order.