A method for detecting a malfunction of a brake system may include measuring a deceleration/acceleration upon braking and determining whether the brake system has the malfunction by comparing the measured deceleration/acceleration and a required deceleration/acceleration. If it is determined that the brake system has the malfunction, the method further includes determining whether a braking interval is an interval where braking is performed only through regenerative braking. If so, the method determines that a regenerative brake system has the malfunction. If not, the method further includes determining whether a left friction brake system or a right friction brake system has the malfunction by measuring a yaw rate value and determining whether a front wheel friction brake system or a rear-wheel friction brake system has the malfunction by using a variation amount of a measurement value of the deceleration/acceleration.