An agent for hair deforming treatment comprising the following components (A) and (B):(A) a compound represented by the following formula (1), and(B) water:wherein R1, R2 and R3 represent H or a group represented by formula (2), and 0 to 2 thereof are H, wherein,in the formula (2), R represents H or a carboxy group, and A1 and A2 represent H, OH or a group represented by formula (3), whereinin the formula (3), any one of X, Y and X represents a site binding to the C in the formula (2), and the others represent H or —CH(OH)COOH.
