An electronic brake comprising: a plurality of wheel brake units (w1, w2, w3, w4) configured to supply a braking force to a plurality of wheels of a vehicle; a main braking device comprising a main braking motor and configured to generate a first brake oil pressure; a secondary braking device comprising a secondary braking motor and configured to generate a second brake oil pressure; a hydraulic circuit valve device configured to selectively transmit, to the plurality of wheel brake units (w1, w2, w3, w4), the first or second brake oil pressure; a main controller configured to control the main braking motor based on a braking input; and an assistant controller configured to: control the secondary braking motor based on the braking input; and control the hydraulic circuit valve device to transmit the second brake oil pressure to a portion of the plurality of wheel brake units (w1, w2, w3, w4) when the main controller or the main braking device malfunctions, characterized in that: the main braking device has a double-acting piston structure including a piston disposed in an internal space of the main braking device and two hydraulic pressure chambers separated by the piston, the secondary braking device comprises an oil pump, a second main braking valve is disposed between a reservoir and a forward chamber positioned in front of the piston of the main braking device, and the second main braking valve is configured to selectively transmit a hydraulic pressure from the secondary braking device to the wheel brake units (w1, w2, w3, w4) depending on whether the second main braking valve is open or closed. a plurality of wheel brake units (w1, w2, w3, w4) configured to supply a braking force to a plurality of wheels of a vehicle; a main braking device comprising a main braking motor and configured to generate a first brake oil pressure; a secondary braking device comprising a secondary braking motor and configured to generate a second brake oil pressure; a hydraulic circuit valve device configured to selectively transmit, to the plurality of wheel brake units (w1, w2, w3, w4), the first or second brake oil pressure; a main controller configured to control the main braking motor based on a braking input; and an assistant controller configured to: control the secondary braking motor based on the braking input; and control the hydraulic circuit valve device to transmit the second brake oil pressure to a portion of the plurality of wheel brake units (w1, w2, w3, w4) when the main controller or the main braking device malfunctions, characterized in that: the main braking device has a double-acting piston structure including a piston disposed in an internal space of the main braking device and two hydraulic pressure chambers separated by the piston, the secondary braking device comprises an oil pump, a second main braking valve is disposed between a reservoir and a forward chamber positioned in front of the piston of the main braking device, and the second main braking valve is configured to selectively transmit a hydraulic pressure from the secondary braking device to the wheel brake units (w1, w2, w3, w4) depending on whether the second main braking valve is open or closed. control the secondary braking motor based on the braking input; and control the hydraulic circuit valve device to transmit the second brake oil pressure to a portion of the plurality of wheel brake units (w1, w2, w3, w4) when the main controller or the main braking device malfunctions, characterized in that: the main braking device has a double-acting piston structure including a piston disposed in an internal space of the main braking device and two hydraulic pressure chambers separated by the piston, the secondary braking device comprises an oil pump, a second main braking valve is disposed between a reservoir and a forward chamber positioned in front of the piston of the main braking device, and the second main braking valve is configured to selectively transmit a hydraulic pressure from the secondary braking device to the wheel brake units (w1, w2, w3, w4) depending on whether the second main braking valve is open or closed. the main braking device has a double-acting piston structure including a piston disposed in an internal space of the main braking device and two hydraulic pressure chambers separated by the piston, the secondary braking device comprises an oil pump, a second main braking valve is disposed between a reservoir and a forward chamber positioned in front of the piston of the main braking device, and the second main braking valve is configured to selectively transmit a hydraulic pressure from the secondary braking device to the wheel brake units (w1, w2, w3, w4) depending on whether the second main braking valve is open or closed.