<p>Disclosed is a cleaning agent for a silicon wafer which has a fine recess/projection pattern in the surface. The cleaning agent contains a cleaning liquid A and a cleaning liquid B. The cleaning liquid A is composed of an aqueous solution, and the cleaning liquid B is used for providing recesses in the recess/projection pattern with water repellency, and is obtained by mixing water or an acidic aqueous solution with an alcohol solution which contains an alcohol solvent and a water-repellent compound containing a hydrophobic group and a hydrolyzable moiety which enables formation of a unit that is chemically bondable with Si in the silicon wafer. The water-repellent compound is blended to be 0.2-20% by mass per 100% by mass of the total of the cleaning liquid B. This cleaning agent can improve the cleaning step wherein pattern collapse is easily induced.</p>
