A defibrillator providing a defibrillation shock including a defibrillation pulse forming a biphasic wave having a first phase and a second phase having polarity opposite that of the first phase, the defibrillator comprising: a high voltage capacitor charged through a battery power source; a ladder bridge circuit connected to one end of the high voltage capacitor; and a control unit configured to control on/off states of switching elements constituting the ladder bridge circuit, wherein the ladder bridge circuit includes a first circuit unit and a second circuit unit having one ends connected to one end of the high voltage capacitor and connected in parallel, and a third circuit unit connected in series to the other ends of the first circuit unit and the second circuit unit, and a fourth circuit unit connected in series to the third circuit unit, the first circuit unit includes a first switching element having one end connected to the high voltage capacitor and a second switching element connected in series to the other end of the first switching element, the second circuit unit includes a third switching element having one end connected to the high voltage capacitor and a fourth switching element connected in series to the other end of the third switching element, the third circuit unit includes a fifth switching element and a sixth switching element connected in parallel and having one ends connected to the other ends of the first circuit unit and the second circuit unit, the fourth circuit unit includes a seventh switching element connected in series to the fifth switching element and an eighth switching element connected in series to the sixth switching element, the seventh switching element and the eighth switching element are connected in parallel, the control unit being configured to control the first switching element, the third switching element, the seventh switching element, and the eighth switching element to always be in an on state. a high voltage capacitor charged through a battery power source; a ladder bridge circuit connected to one end of the high voltage capacitor; and a control unit configured to control on/off states of switching elements constituting the ladder bridge circuit, wherein the ladder bridge circuit includes a first circuit unit and a second circuit unit having one ends connected to one end of the high voltage capacitor and connected in parallel, and a third circuit unit connected in series to the other ends of the first circuit unit and the second circuit unit, and a fourth circuit unit connected in series to the third circuit unit, the first circuit unit includes a first switching element having one end connected to the high voltage capacitor and a second switching element connected in series to the other end of the first switching element, the second circuit unit includes a third switching element having one end connected to the high voltage capacitor and a fourth switching element connected in series to the other end of the third switching element, the third circuit unit includes a fifth switching element and a sixth switching element connected in parallel and having one ends connected to the other ends of the first circuit unit and the second circuit unit, the fourth circuit unit includes a seventh switching element connected in series to the fifth switching element and an eighth switching element connected in series to the sixth switching element, the seventh switching element and the eighth switching element are connected in parallel, the control unit being configured to control the first switching element, the third switching element, the seventh switching element, and the eighth switching element to always be in an on state.