A robot maintenance assist device for predicting a life of a drive system of a robot so as to assist a maintenance, comprising: an acquired data storing unit for storing an acquired data about a current command value of a servo motor configuring the drive system of the robot; a tendency diagnosis unit for diagnosing a future changing tendency of the current command value based on the data of the current command value stored in the acquired data storing unit; a set value change unit for changing a set value used upon a diagnosis in the tendency diagnosis unit; and a life determining unit for determining a term until the current command value reaches a previously set value based on the future changing tendency of the current command value acquired by the tendency diagnosis unit, wherein the tendency diagnosis unit is configured to perform a diagnosis based on the data of the current command value acquired only during an operation of the robot, the tendency diagnosis unit has a function of making a display unit display a prediction line representing the future changing tendency of the current command value as a graph, the life determining unit is configured to determine a time point corresponding to an intersecting point of the prediction line displayed in the graph and a reference line set in the graph as a predicted life, the reference line being determined as a reference value * a threshold value / 100, the set value used upon a diagnosis in the tendency diagnosis unit includes at least one of a threshold value regarding the current command value, a number of object data days from a current date, a number of days from the current date up to a determination date, and a lowest number of data used for a diagnostic operation, the tendency diagnosis unit is further configured to acquire a motor continuous stall current value of the drive system of the robot as a reference, and the life determining unit is configured to determine the term until the current command value reaches the previously set value based on further the acquired motor continuous stall current value which is used as the reference. an acquired data storing unit for storing an acquired data about a current command value of a servo motor configuring the drive system of the robot; a tendency diagnosis unit for diagnosing a future changing tendency of the current command value based on the data of the current command value stored in the acquired data storing unit; a set value change unit for changing a set value used upon a diagnosis in the tendency diagnosis unit; and a life determining unit for determining a term until the current command value reaches a previously set value based on the future changing tendency of the current command value acquired by the tendency diagnosis unit, wherein the tendency diagnosis unit is configured to perform a diagnosis based on the data of the current command value acquired only during an operation of the robot, the tendency diagnosis unit has a function of making a display unit display a prediction line representing the future changing tendency of the current command value as a graph, the life determining unit is configured to determine a time point corresponding to an intersecting point of the prediction line displayed in the graph and a reference line set in the graph as a predicted life, the reference line being determined as a reference value * a threshold value / 100, the set value used upon a diagnosis in the tendency diagnosis unit includes at least one of a threshold value regarding the current command value, a number of object data days from a current date, a number of days from the current date up to a determination date, and a lowest number of data used for a diagnostic operation, the tendency diagnosis unit is further configured to acquire a motor continuous stall current value of the drive system of the robot as a reference, and the life determining unit is configured to determine the term until the current command value reaches the previously set value based on further the acquired motor continuous stall current value which is used as the reference.