A laser processing robot system and a laser processing method, by which the motion accuracy of a robot in the system can be improved and laser processing with high accuracy can be carried out. The robot system is configured to: execute a first robot motion for moving an laser irradiation device to a predetermined command position; measure an actual three-dimensional position of the irradiation device in the first robot motion; calculate a deviation between the command position and the measured actual three-dimensional position of the irradiation device in the first robot motion; store the calculated deviation as a time series of deviation data; and execute a second robot motion in which a robot motion similar to the first robot motion is executed while correcting the laser irradiation position so that the laser irradiation position coincides with a desired position, based on the stored deviation data.