The invention provides a parakeratosis inhibitor, pore-shrinking agent, or rough skin preventing/ameliorating agent that has a function such as parakeratosis inhibition, pore shrinkage, or rough skin-inhibition/abatement, poses no safety problems such as sensory irritation, and is very safe, and further provides an external composition for skin to which a compound having the above-mentioned function has been added. The parakeratosis inhibitor, pore-shrinking agent, or rough skin preventing/ameliorating agent comprises one or more compounds selected from the group consisting of β-alanine derivatives and salts thereof. The external composition for skin comprises the one or more compounds selected from the group consisting of β-alanine derivatives and salts thereof as the above-mentioned parakeratosis inhibitor, pore-shrinking agent, or rough skin preventing/ameliorating agent.