Resin composition for cosmetics, resin composition for manicure, primer for gel manicure, and adhesive for extending eyelashes

An undercoat layer (2), which is an example of a cosmetic resin composition, is used in a cosmetic for adhesion to a nail (1), which is a part of a living body. The resin composition for cosmetics contains a stimuli-responsive material that changes in volume as an external stimuli by external stimuli caused by contact with a solvent and external stimuli other than external stimuli caused by contact with a solution. The contact angle of water with respect to the surface of a cured product of the cosmetic resin composition is 30-110 degrees (inclusive). A cured product of the cosmetic resin composition changes in volume by being imparted with an external stimulus, thereby reducing the strength of adhesion with a part of a living body. 作为化妆品用树脂组合物的一例的底涂层(2)为用于粘接于作为生物体的一部分的指甲(1)的化妆品中使用的化妆品用树脂组合物。化妆品用树脂组合物包含刺激响应性材料，所述刺激响应性材料通过作为外部刺激的、由与溶剂接触带来的外部刺激及除了由与溶液接触带来的外部刺激以外的外部刺激而发生体积变化，相对于化妆品用树脂组合物的固化物的表面的、水的接触角为30°以上且110°以下。化妆品用树脂组合物的固化物通过被赋予外部刺激而发生体积变化，从而与生物体的一部分的粘接强度下降。