Provided is a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may form a pressure-sensitive adhesive having a fine phase separation structure by a block copolymer including a hard segment and a soft segment, and also has a high elastic modulus and an excellent pressure-sensitive adhesive property. For example, although applied to a thin polarizing plate on at least one surface of which a polarizer protective film is not used, the pressure-sensitive adhesive may allow the polarizing plate to exhibit excellent durability, moisture resistance, workability, a pressure-sensitive adhesive property and a light leakage inhibiting ability.