An apparatus for measuring the geometry of the hollow mold compartment of continuous casting molds comprising a measuring head displaceable essentially in the direction of its lengthwise axis and having three impact or contact elements arranged at a first side of the measuring head. The impact elements form a triangle which is parallel to the lengthwise axis of the measuring head. A first measuring feeler is arranged at this first side so as to bear against the neighboring mold wall and is perpendicular to the plane of the triangle and at least one resilient impact element is arranged at a second side of the measuring head opposite the first side and produces a force-vector directed away from the triangle at a right angle. A second measuring feeler is arranged at the second side of the measuring head coaxial to the first measuring feeler and bears against the opposite wall of the hollow mold compartment. Indicator elements operatively connected with the measuring feelers indicate the position thereof.