A novel polymer comprising a reaction product obtained by reacting an organosilane compound with a boron compound. The polymer comprises a reaction product obtained by reacting (a) an aminated silane compound represented by the formula R 4-n -Si-(OR') n (wherein R represents an aminated organic group; R' represetns methyl, ethyl, or propyl; and n is an integer of 1-3) with (b) at least one boron compound selected from the group consisting of H 3 BO 3 and B 2 O 3 , the amount of the ingredient (b) being 0.02 mol or larger per mol of the ingredient (a).