To provide a method for producing an optical fiber preform suitable for production of large-sized optical fiber preform.

This method for producing an optical fiber preform comprises each ejecting flame and a glass raw material from each burner of a core burner 1 and a clad burner equipped with a glass raw material flow outlet, a fuel oil gas flow outlet and supporting gas flow outlet, producing glass fine particles by flame hydrolysis method and depositing these glass fine particles at the lower end of a starting rod which is almost vertically arranged. In this case, plural auxiliary supporting gas flow outlet 37 are arranged in a fuel gas flow outlet 33 of the core burner 1 and formation and deposition of glass fine particles are carried out while ejecting the supporting gas from these auxiliary supporting gas flow outlets 37.