A steering assist device, comprising: an electric motor that applies a steering driving force to a steering operation mechanism of a vehicle; an information obtaining unit that obtains a lateral deviation of the vehicle from a target travel line and a lateral deviation change rate, or a rate of change in the lateral deviation per unit time; a steering torque detector that detects steering torque; a steering assist current value setting unit that sets a steering assist current value corresponding to a target value of steering assist torque; a lane keep assist current value calculation unit that calculates a lane keep assist current value corresponding to a target value of lane keep assist torque that makes the lateral deviation and the lateral deviation change rate closer to zero, based on the lateral deviation and the lateral deviation change rate obtained by the information obtaining unit; and a control unit that drivingly controls the electric motor based on the target current value calculated by the target current value calculation unit characterized in that the steering assist device further comprises a final lane keep assist current value setting unit that sets a final lane keep assist current value to the lane keep assist current value calculated by the lane keep assist current value calculation unit when a steering direction obtained from the detected steering torque detected by the steering torque detector is different from a steered direction corresponding to the lane keep assist current value calculated by the lane keep assist current value calculation unit, and that sets the final lane keep assist current value to zero when the steering direction obtained from the detected steering torque is the same as the steered direction corresponding to the lane keep assist current value; and a target current value calculation unit that calculates a target current value by using the steering assist current value set by the steering assist current value setting unit and the final lane keep assist current value set by the final lane keep assist current value setting unit. an electric motor that applies a steering driving force to a steering operation mechanism of a vehicle; an information obtaining unit that obtains a lateral deviation of the vehicle from a target travel line and a lateral deviation change rate, or a rate of change in the lateral deviation per unit time; a steering torque detector that detects steering torque; a steering assist current value setting unit that sets a steering assist current value corresponding to a target value of steering assist torque; a lane keep assist current value calculation unit that calculates a lane keep assist current value corresponding to a target value of lane keep assist torque that makes the lateral deviation and the lateral deviation change rate closer to zero, based on the lateral deviation and the lateral deviation change rate obtained by the information obtaining unit; and a control unit that drivingly controls the electric motor based on the target current value calculated by the target current value calculation unit characterized in that the steering assist device further comprises a final lane keep assist current value setting unit that sets a final lane keep assist current value to the lane keep assist current value calculated by the lane keep assist current value calculation unit when a steering direction obtained from the detected steering torque detected by the steering torque detector is different from a steered direction corresponding to the lane keep assist current value calculated by the lane keep assist current value calculation unit, and that sets the final lane keep assist current value to zero when the steering direction obtained from the detected steering torque is the same as the steered direction corresponding to the lane keep assist current value; and a target current value calculation unit that calculates a target current value by using the steering assist current value set by the steering assist current value setting unit and the final lane keep assist current value set by the final lane keep assist current value setting unit.