The men had been installing windows on a high-rise apartment building in the Philippines capital when the platform gave way and sent them tumbling from the 32nd to the 7th floor.
One worker survived the fall but was in critical condition.
Building owner Eton Properties Philippines said the workers were employees of its glass contractor and were on a break at the time of the accident.
The workers took the platform to go up the 39-storey building “instead of taking the stairs”, a statement said.
“Since the platform can only carry a few workers, the cable snapped,” it added.
The company has ordered a review of the safety regulations of its subcontractors and construction management.
Mayor Junjun Binay of Makati city, Manila’s financial district ordered construction at the site to be halted “until we are sure that the workers there are safe”.