The present invention provides a sensor and apparatus for measuring flow electric potential for evaluation of a degree of electrodeposition of paint applied to the body or chassis of a vehicle. The sensor includes a base plate part, a dielectric polymer member, a positive (+) electrode terminal and a negative (−) electrode terminal, and an insulation part. The base plate part is mounted on the outer and inner body or chassis of a vehicle, and is electrically connected to ground. The dielectric polymer member is patterned and formed on the base plate part. The positive (+) electrode terminal is connected to the dielectric polymer member and is configured to have a positive (+) polarity. The negative (−) electrode terminal is connected to the base plate part and is configured to have a negative (−) polarity. The insulation part is formed to insulate the positive (+) and negative (−) electrode terminals from each other.