The invention relates to a system for adjusting the height of an agricultural implement, including an arm that can be controlled so as to raise and lower the implement； a height measuring sensor mounted on the arm and positioned in front of the implement in the direction of travel of the vehicle equipped with the arm. A calculator configured to provide a control set point for the height of the arm on the basis of the measurements obtained by the sensor, wherein the sensor is a light screen device formed by an emitter in the form of a column of light sources and a receiver in the form of a column of photoreceptors. The emitter and the receiver are mounted on the arm facing one another and extending along their longitudinal axis, perpendicularly to the ground, in order to measure the height of plants located therebetween.
