This study proposes the development of contamination measurement for industrial machines based on magnetic field method. A permanent magnet was used to generate the 0.17 T magnetic fields and Hall Effect sensor was applied to measure the contamination level of metal particles in industrial machine lubricant during operation time and to predict the replacement period if the lubricant condition does not meet the standard (NAS 1638). Contamination level of metal particles was directly related to the output voltage of Hall Effect sensor. When there was any movement of metal particles to the permanent magnet, the measured result was then transferred to a computer for analysis. This methodology could be applied to experiment the conditions of used lubricant for assessing the contamination and the metal particle remaining in the tank or inside the pipe of the machine as well as the conditions of car lubricant and other lubricants used in industrial processes.