Provided are a beauty care method for improving a skin condition caused by the increase or reduction in corneocyte desquamation, a method for evaluating the reduction or increase in corneocyte desquamation, and a method for screening for a corneocyte desquamation promoting agent or a corneocyte desquamation suppressing agent, in each of which a novel endogenous inhibitor capable of inhibiting the activity of mesotrypsin is used. The present invention is achieved on the basis of a finding that serpin B12 can act as an endogenous trypsin inhibitor which inhibits the activity of mesotrypsin that is known as a protease involved in the starting of corneocyte desquamation.本發明提供一種使用阻礙中胰蛋白酶之活性之新穎之內因性抑制劑的用以改善起因於角質層剝離之促進/抑制之肌膚狀態的美容方法、角質層剝離之抑制/促進之評價方法、及角質層剝離促進劑/角質層剝離抑制劑之篩選方法。本發明係基於如下見解：絲胺酸蛋白酶抑制劑B12係作為阻礙已知為角質層剝離之起始蛋白酶之中胰蛋白酶之活性的內因性胰蛋白酶抑制劑而發揮功能。
