The instrument uses magnetic and eddy current two thickness measurement methods, can be measured without loss of magnetic metal matrix (such as steel, iron, alloy and hard magnetic steel, etc.) on the thickness of non-magnetic coating (such as aluminum, chromium, copper, enamel, Rubber, paint, etc.) and non-magnetic metal substrate (such as copper, aluminum, zinc, tin, etc.) on the thickness of non-conductive coating (such as: enamel, rubber, paint, plastic, etc.).