In this paper, we introduce a new sensor system to measure the vehicle body velocity using a CMOS camera and it's motion blur. When the camera faced on the ground and mounted on the vehicle body is shaken by a specific path to artificially form a motion blur, a Modulated Motion Blur is recorded on the image sensor. This Modulated Motion Blur implies the relative motion between the camera and the ground. The relative velocity of the vehicle and the ground can be estimated by measuring the slopes of the motion blur. In this paper, the invariance of the proposed system against the rolling shutter effect is demonstrated. Then, the performance of the proposed method through various experiments is presented. The proposed method has a small amount of calculation and high accuracy. Therefore, in addition to the dynamic control of the ground vehicle, it can be applied to various fields such as precise position estimation and autonomous driving of a field robot.