PROBLEM TO BE SOLVED: To provide a screening method of finding a material having a horny plug formation suppressing effect.SOLUTION: Using a cultured epidermal keratinocyte obtained from a human donor, a material having a horny plug formation suppressing effect is screened using the amount of keratin 17 as an index. The amount of keratin 17 is used as the index, a test article such as a cosmetic raw material having an effect of reducing the amount can be selected. Without requiring a test using a human, a material having the horny plug formation suppressing effect can be screened simply.COPYRIGHT: (C)2016,JPO&INPIT