A method for monitoring a driving unit of a car body assembly line, and a device therefor. The method includes: storing, for each driving unit, as initial data of the driving unit, information on time length, a peak current, an average current of a constant-speed section, and a current integral area in each sub section on the basis of a time-based current value measured in a normal state of the driving unit; storing, as observation data for each monitoring factor, information on the time length, the peak current, the average current of the constant-speed section, and the current integral area in each sub section, for each operating section observed during an operation of the driving unit; and individually comparing each piece of the information with a threshold level of the initial data, and providing state monitoring information of the driving unit, for each monitoring factor.