A composition for a pressure-sensitive adhesive, includes (A) a (meth)acrylic ester polymer having a trithiocarbonate structure, having hydroxyl groups at both ends of a molecule and having a weight-average molecular weight (Mw), as measured by gel permeation chromatography, of 50,000 to 300,000, and (B) an isocyanate compound having an average number of isocyanate groups in one molecule being more than 2.