This invention provides automatic measuring apparatus for measuring the amount of wax, oil and other substances applied on a specified portion of a workpiece. A controller unit controls cleaning, measuring and calculating operations. Under such control, the workpiece set in a cleaning device is automatically cleaned using an appropriate solvent. The solvent used for cleaning the workpiece is automatically supplied to a measuring device and the absorption spectrum of the solvent is measured. Based on the data of the absorption spectrum measured by the measuring device, a calculating device automatically calculates the application amount of the wax, the oil or the other substances applied over the workpiece. The automatic measuring apparatus thus enhances measuring precision and reduces the time period required for the measuring operation. During the cleaning operation prior to the measuring operation, the solvent is sealed and prevented from leaking in the cleaning device, thereby assuring a safe operating environment.