Disclosed is a boron adsorbent having an excellent adsorbing ability against boron contained in a solution, which is inexpensive and has high general versatility. Also disclosed is a boron removal method which can remove boron efficiently in a simple manner. An amide derivative represented by the general formula (1) is added to a boron-containing water under alkaline conditions to cause the adsorption of boron to the amide derivative. Then, a cation source having two or more valencies is added to the water to cause the aggregation of the amide body. The aggregated amide body is removed from the water. In the general formula (1), m represents 1 or 2; X represents —CH2OH, —CHO or —COOH; n represents an integer of 2 to 5; X are independent from each other and n are independent from each other when m represents 2; and Y represents a monovalent hydrocarbon group having 6 to 16 carbon atoms when m is 1, and represents a divalent hydrocarbon group having 8 to 18 carbon atoms when m is 2.