PROBLEM TO BE SOLVED: To establish a method allowing discovery of excellent skin whitening effect and accurate and efficient evaluation of the skin whitening effect.SOLUTION: Deactivation effect on a signaling system via Proadrenomedullin N-terminal 20 peptide (PAMP) and/or Adrenomedullin 2/Intermedin (ADM2/IMD) binding receptors is employed as an indicator so that an excellent skin whitening component can be accurately and easily selected. Further, a composition containing this component exhibits excellent pigmentation preventing or improving effect.