The present invention relates to a measuring device for the bend angle of a metal sheet or plate in a press brake of the type having a reciprocable punch with a sharp bending edge, and a die having two bending edges on either side of a substantially V-shaped groove or channel, the measuring device comprising a rotatory measuring element, the cross-section of which has a circular peripheral part centered around the axis of rotation of the measuring element, and a linear peripheral part which is shorter than the diameter of the circular peripheral part.