To provide a parakeratosis inhibitor, pore reducing agent and skin roughness preventing/ameliorating agent that exhibit capabilities of parakeratosis inhibition, pore reduction, skin roughness prevention/amelioration, etc., and further provide a skin preparation for external use having these capabilities. There are provide a parakeratosis inhibitor and a pore reducing agent each comprising at least one compound selected from the group consisting of a glycine derivative, an aminodicarboxylic acid derivative, an acylaminodicarboxylic acid derivative, a pyrrolidinecarboxylic acid derivative, a piperidinecarboxylic acid derivative, a hexamethyleneiminecarboxylic acid, a beta-alanine derivative and salts of these derivatives. Further, there are provided a parakeratosis inhibitor, a pore reducing agent and a skin roughness preventing/ameliorating agent each comprising at least one compound selected from the group consisting of specified glycine derivatives and salts thereof and specified aminosulfuric acid derivatives and salts thereof. Still further, there are provided skin preparations for external use comprising these compounds.