Curable composition

A curable composition, which comprises a polymer (A) having a polyoxyalkylene main chain and a reactive silicon group represented by the following formula (1) and an amidine derivative salt (B) represented by the following formula (2):

• —SiX1aR13-a (1)
• wherein R1 is a C1-20 monovalent organic group (excluding a hydrolyzable group) which may have a substituent, X1 is a hydroxy group or a hydrolyzable group, and “a” is an integer of from 1 to 3, provided that when there are a plurality of R1's, the plurality of R1's may be the same or different, and when there are a plurality of X1's, the plurality of X1's may be the same or different,
• wherein R2 is a hydrocarbon group in which the carbon atom at the α-position to the nitrogen atom is a carbon atom having no unsaturated bond, or a hydrogen atom, each of R3 and two R4's which are independent of one another, is an organic group or a hydrogen atom, R5 is a C1-25 linear or branched saturated or unsaturated hydrocarbon group or a hydrogen atom, and X2 is an organic acid ion, an inorganic acid ion or a hydroxy group, and optional two or more of R2, R3 and two R4's may be bonded to form a cyclic structure,
• wherein (B) is a p-toluene sulfonic acid salt or a formic acid salt.