A wafer processing method includes: a holding step of holding a wafer on a chuck table through a dicing tape; and a dividing step of cutting the wafer along division lines by a cutting blade. In the dividing step, cleaning water including pure water mixed with carbon dioxide is supplied to the front surface of the wafer, and cutting water including pure water alone or pure water mixed with carbon dioxide in a concentration lower than that of the cleaning water is supplied to the cutting blade. During cutting, therefore, the cleaning water and the cutting water are always shielded by each other. Consequently, the cutting blade can be prevented from being corroded or excessively worn due to the cleaning water, and the cutting water can be prevented from contacting the front surface of the wafer to cause electrostatic discharge damage to the devices.