Transmission function and reception function and that increase of circuit scale of the circuit which is annexed is prevented, the small size lightweight ultrasonic diagnostic device the ultrasonic probe which is used for that is offered. Because of that, it uses the pre-amp 16 for reception which is accommodated inside ultrasonic probe 1, the power source terminal of the particular pre-amp combining with the floating section (diode 15 and condenser 12) which is separated with drive power source Vdd and Vss. As for the aforementioned floating section, when transmitting by the fact that floating it can point to the electric potential of the pre-amp itself electrically, the function which protects the particular pre-amp from transmission pulse of high tension is carried out, in addition, when receiving bias electric potential of the pre-amp recovers, the particular pre-amp is used as the pre-amp for usual reception.送信機能及び受信機能とその付随する回路の回路規模の増大を防ぎ、小型・軽量な超音波診断装置とそれに用いる超音波探触子を提供する。そのために、超音波探触子1内に収容された受信用プリアンプ16を、当該プリアンプの電源端子を駆動電源Vdd,Vssと切り離すフローティング部(ダイオード15及びコンデンサ12)と組み合わせて用いる。前記フローティング部は、送信時にはプリアンプ自体の電位を電気的にフローティングさせる事で、高電圧の送信パルスから当該プリアンプを保護する機能を果たし、また、受信時にはプリアンプのバイアス電位が回復し、当該プリアンプが通常の受信用プリアンプとして使用される。
