System of the present invention provide a kind of water-fast epithelium formed can it is higher, can get the excellent esterification reaction product of bright sense, moisture block property. The esterification reaction product is by being esterified following compositions A, ingredient B and ingredient C and winner:Ingredient A: 12- hydroxy stearate acid polymer more than haptamerIngredient B: the fatty acid in addition to 12- hydroxy stearate acid polymerIngredient C: pentaerythrite.本發明係提供一種耐水皮膜形成能較高、可獲得光亮感、水分封鎖性優異之酯化反應生成物。該酯化反應生成物係藉由使下述成分A、成分B、及成分C酯化而獲得者：成分A：七聚物以上之12-羥基硬脂酸聚合物成分B：除12-羥基硬脂酸聚合物以外之脂肪酸成分C：季戊四醇。
