The present invention relates to a handpiece for an ultrasonic device, comprising a handpiece main body and a cartridge attachable to and detachable from the handpiece main body. The handpiece main body comprises: a main body housing an actuator, installed in the main body housing, for axially transferring a transducer an operating button mounted on the main body housing and a handpiece main substrate for operating the actuator according to the control of a controller main body, supplying and cutting-off power to the transducer according to on/off operations of the operating button, and receiving, as an input, a signal detected by the transducer and transmitting the signal to the controller main body. The cartridge comprises: a cartridge housing a transducer, built in the cartridge housing, for generating point-focused or line-focused ultrasound a guide pin for axially guiding the transducer a magnet for power transfer for transferring the power of the actuator to the cartridge a slider for axially moving the transducer along the guide pin by the operation of the actuator a window, formed on one side of the cartridge housing, for transferring the ultrasound generated by the transducer to a patient and a bellows for isolating liquid contained in the cartridge housing and helping easy transfer of the slider.La présente invention porte sur une pièce à main pour un dispositif à ultrasons, laquelle pièce comporte un corps principal de pièce à main et une cartouche pouvant être fixée au corps principal de pièce et détachée à partir de celui-ci. Le corps principal de pièce à main comprend : un boîtier de corps principal un actionneur, installé dans le boîtier de corps principal, pour transférer axialement un transducteur un bouton dactionnement monté sur le boîtier de corps principal et un substrat principal de pièce à main pour actionner lactionneur en fonction de la commande dun corps principal de dispositif de commande, délivrer et interrompre une alimentation vers l
