An ultrasonic energy therapy device including: an insertion portion that has an elongated shape and is insertable into a blood vessel； a piezoelectric element that is attached to the insertion portion and radiates ultrasonic energy from inside of the blood vessel toward a biological tissue outside the blood vessel； a thermometric sensor； a temperature detection section that detects the temperature of the thermometric sensor； and a control section that controls the piezoelectric element depending on the temperature of the thermometric sensor measured by the temperature detection section so that the ultrasonic energy in a desired amount is radiated to the biological tissue.
