PURPOSE: To obtain a self-adhesive composition which has excellent adhesiveness, cohesive force and heat resistance and can prevent an adherent and a support from being hydrolyzed by adding a dialkylamine or a trialkylamine to a specified acrylic copolymer.

CONSTITUTION: The title self-adhesive composition is formed by adding 1-20 pts.wt. dialkylamine or trialkylamine (each alkyl group having at least 4C) to 100 pts.wt. acrylic copolymer formed by copolymerizing 85-97wt.% (meth) acrylic ester with 3-15wt.% carboxylic compound. When the proportion of the carboxylic compound in the copolymer is lower, the cohesive force of the adhesive decreases. When it is higher, the adhesiveness decreases and the adhesive accelerates the hydrolysis of an adherend or a support. When the proportion of the dialkylamine or trialkylamine is lower, the effect of the carboxylic compound on the prevention of hydrolysis decreases. When it is higher, the adhesive softens and its adhesiveness and cohesive force decrease.