An electric brake system is disclosed. The electric brake system controlling a hydraulic pressure delivered to a wheel cylinder provided at each of wheels according to a pedal effort of a brake pedal, includes a reservoir configured to store oil; a master cylinder including first and second hydraulic ports, each of which is connected to two wheels, and configured to generate a hydraulic pressure by the pedal effort of the brake pedal; a pedal simulator configured to provide a reaction force of the brake pedal by being connected to the master cylinder, and connected to the reservoir; a simulation valve installed at an oil flow path connecting the pedal simulator to the reservoir, or at an oil flow path connecting the master cylinder to the pedal simulator; a bypass flow path branching off from the oil flow path and connected to the reservoir; and a relief valve provided at the bypass flow path and configured to enable oil to flow when the simulation valve operates abnormally.