An adsorbent of the invention, which is an adsorbent for removing carbonyl sulfide in a stream containing an olefin, contains copper oxide and an aluminum compound, in which a content of the aluminum compound ranges from 10 mass % to 50 mass % in terms of Al, and an NH3 desorption in a temperature region ranging from 100 degrees C. to 200 degrees C. as measured by NH3-TPD measurement is more than 0.001 mmol/g and 1 mmol/g or less.