In an apparatus and method of generating an ultrasonic vibration, an ultrasonic vibration generated in an ultrasonic vibration generator is transmitted through a material layer to control the intensity and the direction of the ultrasonic vibration. In an apparatus and method of cleaning a wafer, a cleaning solution supplier supplies a cleaning solution for cleaning the wafer onto the wafer. An ultrasonic vibration generator generates an ultrasonic vibration. The ultrasonic vibration is transmitted through a material layer of a transmission member to control the intensity and the direction of the ultrasonic vibration. The ultrasonic vibration is applied to the cleaning solution.