SPEED REDUCER FAILURE STATE NOTIFICATION DEVICE, MECHANICAL SYSTEM HAVING SPEED REDUCER FAILURE STATE NOTIFICATION FUNCTION AND SPEED REDUCER FAILURE STATE NOTIFICATION PROGRAM

PROBLEM TO BE SOLVED: To provide a speed reducer failure state notification device capable of accurately notifying the failure state of a speed reducer even in different use conditions.SOLUTION: A speed reducer failure state notification device for notifying the failure state of a speed reducer of an industrial robot includes a speed reducer and a lubricant deterioration sensor having a clearance forming member with an oil clearance for the lubricant of the speed reducer to enter, the oil clearance being arranged on an optical path from a white LED to an RGB sensor. A threshold is set (S226) in response to the inputted temperature (S222) of the lubricant. When the color difference E (S227) between the color detected by the RGB sensor and black color reaches the threshold (Yes in S228 and No in S229, or Yes in S228 and Yes in S229), the failure state of the speed reducer corresponding to the threshold is notified (S230 and S231).