PROBLEM TO BE SOLVED: To provide a method for producing an optical fiber, which provides high productivity and which prevents the formation of a preform's defect which is a factor of an increased optical transmission loss and decreased fiber strength. SOLUTION: According to the method, an optical fiber containing 30 to 80 mol% Bi 2 O 3 is produced by drawing a core-clad structure preform obtained via steps (a) to (e): (a) inserting a core-forming glass rod with an acid-washed surface into a first clad-forming glass pipe, (b) heat-drawing the assemblage while diminishing the pressure in the clearance between the core-forming glass rod and the first clad-forming glass pipe to make a first core-clad structure preform, (c) inserting the first core-clad structure preform after acid-washing its surface into a second clad-forming glass pipe, (d) heat-drawing the resultant assemblage while diminishing the pressure in the clearance between the first preform with the acid-washed surface and the second clad-forming glass pipe to make a second core-clad structure preform, and (e) acid-washing the surface of the second preform. COPYRIGHT: (C)2006,JPO&NCIPI