A method of monitoring a tool clamping device mounted on a machine spindle, the clamping force of which tool clamping device is generated by a spring assembly which exerts a force in the direction of the clamping position on an actuating element actuating the clamping or the release of a tool or tool holder. In the method, the spring force and the displacement of the actuating element are continuously measured during the release and/or clamping of a tool or tool holder and recorded as functions of the time. These recorded functions are used to identify at least one parameter characteristic for the status of the tool clamping device. Based on the spring force and the displacement over time, a spring characteristic curve is plotted in the form of the spring force as a function of displacement, the analysis of which spring characteristic curve provides information about a number of characteristic parameters.