Police said the accident happened on Saturday afternoon at the site, where a contractor was building a seven-floor building.
The two victims were identified as Charnnarong Kurachinda, 21, and Thongbai Kanhabutr, 29.
They were riding with another worker and a load of paving tiles on a platform being hoisted by crane from the ground to the seventh floor.
But when the platform reached the fifth floor, it started to shake. The third worker, who was frightened, jumped off on to the building, after which the sling broke and the two other men fell to the ground.
They were rushed to the intensive care unit of the hospital, but doctors could not save them.
Following the accident, Chatmongkol Angkhasakulkiart, mayor of Si Sa Ket Municipality, ordered suspension of construction pending an investigation into the accident.