A vehicle lamp device and a light cut-off structure thereof are disclosed. The light cut-off structure includes a front cut-off edge, a rear cut-off edge, and a top surface. The front cut-off edge corresponds in position to the rear cut-off edge and the top surface is connected between the front and rear cut-off edges. A portion of the top surface is inclined along an inclination direction from the front cut-off edge toward the rear cut-off edge. The portion has a predetermined inclination angle relative to a horizontal plane or a lens optical axis. The predetermined inclination angle is greater than 0 degrees and less than 30 degrees. A lighting pattern with a cut-off line is formed when at least one emitted light is selectively shielded by the front cut-off edge. Therefore, the light concentration ratio can be significantly raised.