To obtain a hydrazine derivative having both low-temperature curability and storage stability, capable of forming a coating film having excellent water resistance, hardness, or the like, by making the composition include a specific compound and a specified photostabilizer and/or a prescribed ultraviolet light absorber.

This composition comprises (A) a polyhydrazine compound containing two or more hydrazine residues in one molecule and (B) (i) a photostabilizer containing a hydrazine residue and/or (ii) an ultraviolet light absorber containing a hydrazine residue. A semicarbazide derivative of the formula [R1 is a 2-20C alkylene diisocyanate, a (substituted) 5-25C cycloalkylene diisocyanate or the like; R2 is H or a 1-20C alkyl; R3 is a 1-20C alkylene, a (substituted) 6-10C arylene or the like; (n) is 0 or 1; (l) and (m) are each 0 or a positive integer and 20≥(l+m)≥3], or the like, are preferable as the component A. A hindered phenol derivative containing a hydrazine residue, or the like, are preferably used as the component (i).