PURPOSE: To titled yarn having sufficient stability to deterioration and coloring after dry cleaning since a stabilizer is slightly extracted with a solvent for dry cleaning, obtained by adding a specific phenolic compound as the stabilizer to the yarn.

CONSTITUTION: 100pts.wt. polyurethane elastic yarn is blended with preferably 0.5W10pts.wt. phenolic compound shown by the formula (R1 is 1W6C alkyl; R2 is 4W9C alkyl, aralkyl, etc.; R3 and R4 are H, or methyl; n is 5W20 integer) as a stabilizer, to give the aimed polyurethane elastic yarn. The use of the compound together with an aliphatic tertiary amine group-containing polyurethane preferably improves more stabilizing effect. The compound shown by the formula, for example, is obtained by condensing a p-alkylphenolic compound with dicyclopentadiene, reacting the condensate with an isobutylene gas.