PURPOSE: To produce an excellent composition for dissolving sulfur containing a sulfide compd. and polyalkylene oxyamine containing a primary or secondary functional group of polyamine in a catalytic amount.

CONSTITUTION: A compd. expressed by a formula R1SSaSR2 (R1 and R2 are alkyl, alkoxyalkyl, hydroxyalkyl (carbon number in these alkyl parts, is 1-24; (a) is 0-3 in an average number of an inside sulfur atom in sulfide and at least one kind of polyalkyleneoxyamine or polyamine containing a primary or a secondary functional group (carbon number is 2-4 in an alkylene group except a substd. group) are mixed. The objective compd. is obtained by adding an aliphat. amine, aryl amine, alkalyl amine, etc. as required. Polysulfide is obtained by allowing disulfide or low rank polysulfide to react with the sulfur in the presence of polyalkylene oxamine or polyamine.