A lane keeping assist device comprising: a lateral direction displacement obtaining means configured to obtain information concerning a lateral direction displacement of a vehicle with respect to a traffic lane; a lateral direction displacement threshold value setting means configured to set a lateral direction displacement threshold value(LAL,LAR) for the traffic lane in which the vehicle travels; a first control amount calculating means configured to calculate a first control amount (φL_Rt, φL_Lt) for decreasing a lateral displacement deviation (ΔXR, ΔXL) of the vehicle from the lateral direction displacement threshold value (LAL,LAR); and a travelling direction controlling means configured to: control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis at least the first control amount (φL_Rt, φL_Lt), characterized by a second control amount calculating means configured to calculate a second control amount (φY_Rt, φY_Lt) for decreasing an angle deviation of a travelling direction of the vehicle with respect to the traffic lane, wherein the travelling direction controlling means configured to: control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis of the second control amount (φY_Rt, φY_Lt) when the vehicle is at a center side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane, and control at least one of the turning angle, the turning torque, the braking/driving amount, and the braking/driving force of a road wheel, on the basis of at least the first control amount (φL_Rt, φL_Lt) when the vehicle is at an outer side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane. a lateral direction displacement obtaining means configured to obtain information concerning a lateral direction displacement of a vehicle with respect to a traffic lane; a lateral direction displacement threshold value setting means configured to set a lateral direction displacement threshold value(LAL,LAR) for the traffic lane in which the vehicle travels; a first control amount calculating means configured to calculate a first control amount (φL_Rt, φL_Lt) for decreasing a lateral displacement deviation (ΔXR, ΔXL) of the vehicle from the lateral direction displacement threshold value (LAL,LAR); and a travelling direction controlling means configured to: control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis at least the first control amount (φL_Rt, φL_Lt), characterized by a second control amount calculating means configured to calculate a second control amount (φY_Rt, φY_Lt) for decreasing an angle deviation of a travelling direction of the vehicle with respect to the traffic lane, wherein control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis at least the first control amount (φL_Rt, φL_Lt), characterized by a second control amount calculating means configured to calculate a second control amount (φY_Rt, φY_Lt) for decreasing an angle deviation of a travelling direction of the vehicle with respect to the traffic lane, wherein the travelling direction controlling means configured to: control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis of the second control amount (φY_Rt, φY_Lt) when the vehicle is at a center side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane, and control at least one of the turning angle, the turning torque, the braking/driving amount, and the braking/driving force of a road wheel, on the basis of at least the first control amount (φL_Rt, φL_Lt) when the vehicle is at an outer side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane. control at least one of a turning angle, a turning torque, a braking/driving amount, and a braking/driving force of a road wheel, on the basis of the second control amount (φY_Rt, φY_Lt) when the vehicle is at a center side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane, and control at least one of the turning angle, the turning torque, the braking/driving amount, and the braking/driving force of a road wheel, on the basis of at least the first control amount (φL_Rt, φL_Lt) when the vehicle is at an outer side of the lateral direction displacement threshold value (LAL,LAR) in a width direction of the traffic lane.