To provide a cleaner and a cleaning method which enable the ultrasonic cleaning of a substrate without damage even if it is a damage-susceptable substrate such as a semiconductor wafer, a photomask substrate and a liquid crystal substrate.

An ultrasonic cleaner 1 is a cleaner to ultrasonic clean an object to be cleaned 10 and is provided with at least an ultrasonic vibrator 3 which generates an ultrasonic vibration and a cleaning liquid 9 where the ultrasonic vibrator is installed and the ultrasonic vibration is applied and a means 2 which contacts the object to be cleaned and the ultrasonic vibrator gives the ultrasonic vibration in the transverse direction against the surface where the ultrasonic vibrator is installed and cleans the object to be cleaned by applying the ultrasonic vibration to the cleaning liquid.

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