An electric brake system comprising: a hydraulic pressure supply device configured to generate a hydraulic pressure by operating a hydraulic piston by an electrical signal output in response to displacement of a brake pedal and comprising a first pressure chamber formed at one side of the hydraulic piston movably accommodated in a cylinder block and a second pressure chamber formed at the other side of the hydraulic piston; and a hydraulic control unit comprising a first hydraulic circuit configured to control a hydraulic pressure transmitted to two wheel cylinders and a second hydraulic circuit configured to control a hydraulic pressure transmitted to the other two wheel cylinders, wherein the hydraulic control unit comprises a first hydraulic flow path communicating with the first pressure chamber, second and third hydraulic flow paths (212, 213) branched out from the first hydraulic flow path and respectively connected to the first and second hydraulic circuits (201, 202), a fourth hydraulic flow path communicating with the second pressure chamber, fifth and sixth hydraulic flow paths (215, 2016) branched out from the fourth hydraulic flow path and respectively connected to the first and second hydraulic circuits (201, 202), and a seventh hydraulic flow path connecting the second hydraulic flow path with the third hydraulic flow path, characterized in that the hydraulic control unit comprises a first valve provided at the second hydraulic flow path between a point connected to the seventh hydraulic flow path and the first hydraulic circuit to control a flow of a pressurized medium, a second valve provided at the third hydraulic flow path between a point branched out into the second hydraulic flow path and a point connected to the seventh hydraulic flow path to control a flow of the pressurized medium, a third valve provided at the fifth hydraulic flow path to control a flow of the pressurized medium, a fourth valve provided at the sixth hydraulic flow path to control a flow of the pressurized medium, and a fifth valve provided at the seventh hydraulic flow path to control a flow of the pressurized medium. a hydraulic pressure supply device configured to generate a hydraulic pressure by operating a hydraulic piston by an electrical signal output in response to displacement of a brake pedal and comprising a first pressure chamber formed at one side of the hydraulic piston movably accommodated in a cylinder block and a second pressure chamber formed at the other side of the hydraulic piston; and a hydraulic control unit comprising a first hydraulic circuit configured to control a hydraulic pressure transmitted to two wheel cylinders and a second hydraulic circuit configured to control a hydraulic pressure transmitted to the other two wheel cylinders, wherein the hydraulic control unit comprises a first hydraulic flow path communicating with the first pressure chamber, second and third hydraulic flow paths (212, 213) branched out from the first hydraulic flow path and respectively connected to the first and second hydraulic circuits (201, 202), a fourth hydraulic flow path communicating with the second pressure chamber, fifth and sixth hydraulic flow paths (215, 2016) branched out from the fourth hydraulic flow path and respectively connected to the first and second hydraulic circuits (201, 202), and a seventh hydraulic flow path connecting the second hydraulic flow path with the third hydraulic flow path, characterized in that the hydraulic control unit comprises a first valve provided at the second hydraulic flow path between a point connected to the seventh hydraulic flow path and the first hydraulic circuit to control a flow of a pressurized medium, a second valve provided at the third hydraulic flow path between a point branched out into the second hydraulic flow path and a point connected to the seventh hydraulic flow path to control a flow of the pressurized medium, a third valve provided at the fifth hydraulic flow path to control a flow of the pressurized medium, a fourth valve provided at the sixth hydraulic flow path to control a flow of the pressurized medium, and a fifth valve provided at the seventh hydraulic flow path to control a flow of the pressurized medium.