an apparatus for maintaining and supplying stable power to a skin care device comprising a dc - dc converting unit for escalating the voltages from a charged battery power source , a skin - stimulating unit with a supersonic element or an ion - inducing element , a switch unit having a main switch and various functional switches , an lcd displayer for indicating various operating modes , a cpu for controlling each component , a main switch initiating unit having a function when the main switch is turned on , the cps is activated by a switching signal inputted to an analogue input port from said cpu , the first switch unit is activated by the cpu through an analogue output port , then the fet is switched to supply battery power to the dc - dc - converting unit , and a function of the pwm control signal , which prolongs the switching - on stage for gradually increasing the voltage up to the operating voltage during the step - up stage , and inversely shortens the switching - off stage for gradually decreasing the operating voltage during the step - down stage . a strength - adjusting switch for controlling the strength of output voltage of the dc - dc converting unit , and a mode switch for operating various modes of supersonic vibrations controlled by each vibrating frequency . an led displayer being equipped with a minimum number of connecting pins for indicating various operating modes . each led is independently activated to turn on and off according to each signal of the input - output terminal from a controlling unit of the cpu .