To provide a hardly colored curable composition having an excellent storage stability while maintaining fast curing properties.A curable composition which comprises a polymer (P) having a polyoxyalkylene chain and a group of the following formula (1) and a compound (S) having a mercapto group and a group of the following formula (2), and which contains from 0.01 to 0.50 part by mass of the compound (S) per 100 parts by mass of the polymer (P): --Si(--X.sup.1).sub.3 (1) --Si(--X.sup.2).sub.m(--Y.sup.2).sub.3-m (2) wherein symbols have the following meanings: X.sup.1 and X.sup.2: each independently a C.sub.1-6 alkoxy group, Y.sup.2: a C.sub.1-6 alkyl group, and m: 1, 2 or 3.