The present invention provides a photolabile protecting group that can be removed by light irradiation under mild conditions. More specifically, the present invention provides a method comprising protecting a reactive functional group (e.g., a hydroxyl group, amino group, carboxyl group, carbonyl group, phosphodiester group, etc.) by the photolabile protecting group, and then removing the photolabile protecting group simply by light irradiation under neutral conditions.The present invention relates to a compound represented by Formula (3): wherein Ar1 is an optionally substituted aromatic or heteroaromatic ring, Ar2 is an optionally substituted aryl or heteroaryl group, X is a leaving group, and n is an integer of 1 or 2; and a method of protecting and deprotecting an amino group etc. using the compound.