PURPOSE: To reduce loss time in drawing by judging transfer from noneffective part of a base material tip to effective part thereof based on the measurement of weight of an optical fiber base material and changing diameter of the optical fiber to a prescribed size from the point of time in drawing of optical fiber.

CONSTITUTION: When an optical fiber is produced by drawing optical fiber 4 from the heating and melting part at the tip of an optical fiber base material 2 while heating the optical fiber base material 2 in heating furnace, the following constitution is adapted: the weight of noneffective part which is the weight of noneffective part 2B of the tip of optical fiber base material 2 used is previously estimated and optical fiber 4 is drawn into fiber having a diameter thicker than fiber diameter required while measuring weight of optical fiber base material 2 (using a measuring device 9 and display device 11), and after weight of noneffective part 2B is removed from the weight of optical fiber base material 2, the drawing of fiber with required diameter is started.