A hanger trolley system includes: a driving chain provided in a power rail; a hanger trolley including a hanger dog attached to and detached from a chain dog provided in the driving chain and moving along a free rail formed below the power rail; and a sensor confirming coupling between the chain dog and the hanger dog. A coupled state between the chain dog provided in the driving chain and the hanger dog provided in the hanger trolley is confirmed through the sensor, such that judgment on succession when the hanger trolley is succeeded from a pre-process driving chain to a post-process driving chain becomes clearer as compared with the related art.