An ultrasonic diagnosis and treatment system having a thin tube which is capable of being inserted into a body cavity, and which has at its extreme end an observing ultrasonic vibrator for emitting ultrasonic waves for observation and a treating ultrasonic vibrator for emitting strong ultrasonic waves for treatment. Observation and treatment are performed by using ultrasonic wave. The system further includes a processing device for performing an operation other than the ultrasonic treatment at least on a region observed by using ultrasonic waves. A guide for enabling the processing device to reach the region observed by using ultrasonic waves is provided on the thin tube.