A portable HIFU skin care device comprising: a main body having a rechargeable battery embedded therein, a power button and a step button installed therein for adjusting the intensity of an ultrasonic wave, and a display for displaying operation states of the device, including the number of shots; a cartridge used by being mounted on a head part of the main body and having a HIFU transducer embedded therein; and a cradle comprising a charging part installed therein and capable of charging by being connected with an adaptor, and configured to accommodate the main body via a placement groove and charge an internal battery of the main body while the cartridge is attached to the main body, wherein: a PCB in which a control unit for the cartridge is installed is installed on a rear surface protrusion part on an exterior of a cartridge housing, and when the PCB is mounted on the main body, a connector terminal part of the PCB and a connector installed on the head part of the main body are electrically connected to each other; a transducer moving mechanism including a piezoelectric motor is installed in a first chamber inside the cartridge; the housing of the HIFU transducer is positioned inside a second chamber, which protrudes toward a front surface in a smaller width than the first chamber while communicating with the first chamber; and the protruding surface of the second chamber is configured as an action part brought into surface contact with the object. a main body having a rechargeable battery embedded therein, a power button and a step button installed therein for adjusting the intensity of an ultrasonic wave, and a display for displaying operation states of the device, including the number of shots; a cartridge used by being mounted on a head part of the main body and having a HIFU transducer embedded therein; and a cradle comprising a charging part installed therein and capable of charging by being connected with an adaptor, and configured to accommodate the main body via a placement groove and charge an internal battery of the main body while the cartridge is attached to the main body, wherein: a PCB in which a control unit for the cartridge is installed is installed on a rear surface protrusion part on an exterior of a cartridge housing, and when the PCB is mounted on the main body, a connector terminal part of the PCB and a connector installed on the head part of the main body are electrically connected to each other; a transducer moving mechanism including a piezoelectric motor is installed in a first chamber inside the cartridge; the housing of the HIFU transducer is positioned inside a second chamber, which protrudes toward a front surface in a smaller width than the first chamber while communicating with the first chamber; and the protruding surface of the second chamber is configured as an action part brought into surface contact with the object. a PCB in which a control unit for the cartridge is installed is installed on a rear surface protrusion part on an exterior of a cartridge housing, and when the PCB is mounted on the main body, a connector terminal part of the PCB and a connector installed on the head part of the main body are electrically connected to each other; a transducer moving mechanism including a piezoelectric motor is installed in a first chamber inside the cartridge; the housing of the HIFU transducer is positioned inside a second chamber, which protrudes toward a front surface in a smaller width than the first chamber while communicating with the first chamber; and the protruding surface of the second chamber is configured as an action part brought into surface contact with the object.