The present invention can improve the recognition performance of a traffic sign board, improve the recognition performance of a reflective traffic sign board and a light emitting type traffic sign board by adjusting an exposure of a camera, improve the recognition performance of the reflective traffic sign board and the light emitting type traffic sign board by adjusting gain of an image signal, and improve the recognition performance of the reflective traffic sign board and the light emitting type traffic sign board by simultaneously adjusting the exposure of the camera and the gain of the image signal. In an image recognition system for a vehicle for traffic sign board recognition according to the present invention, an exposure time of a camera lens or gain of an image output from an image sensor is adjusted to generate at least one image group including a plurality of frames in which the exposure time and the gain are different from each other, sign board regions of the plurality of frames are compared with each other, and an image nearest to a predetermined set value is selected.