A magnetic conductive coverplate of leakage type that may used in magnetic holding devices covers a holding surface of the magnetic holding device. The leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material. The leakage type magnetic conductive coverplate can conduct magnetic force of the holding device into a workpiece so as to hold it. Because the leakage type magnetic conductive coverplate is made integrally of a single magnetic conductive material, when there is any change in ambient temperature, no crevice will be produced due to different coefficients of expansion and contraction. Therefore, any coolant used in workpiece machining and any magnetic conductive impurities will not infiltrate into or enter the magnetic holding device to lose the internal insulation, thus effectively protecting the internal structure of the magnetic holding device and remarkably improving durability and service life of the magnetic holding device.