An electric brake system is disclosed. The electric brake system comprises a master cylinder connected to a first reservoir storing oil therein, provided with first and second chambers and first and second pistons respectively provided at the first and second chambers, and configured to discharge oil according to a pedal effort of a brake pedal; a simulation device configured to provide a reaction force according to the pedal effort of the brake pedal, and provided with a simulation chamber that is connected to the master cylinder and a simulation flow path to accommodate oil therein; a hydraulic pressure supply device configured to generate hydraulic pressure using a rotational force of a motor that is activated in response to an electrical signal output corresponding to a displacement of the brake pedal; and a hydraulic control unit configured to deliver the hydraulic pressure delivered from the hydraulic pressure supply device to a wheel cylinder provided at each of wheels, and connected to the first and second chambers of the master cylinder through first and second backup flow paths and connected to the hydraulic pressure supply device through a hydraulic flow path, wherein hydraulic pressure provided from the master cylinder is selectively delivered to the simulation flow path and the first and second backup flow paths.