To provide a method for simultaneous coating of an optical fiber with two layers, which facilitates the regulation of uneven thickness prevention by fixing at least any one among a nipple, primary coating die and secondary coating die and moving the other two in alignment in a horizontal direction, thereby regulating the uneven thickness.

The nipple 15 is held fixed and the primary coating die 16 and the secondary coating die 17 are horizontally moved in alignment by manipulating the horizontal presser 33 of an alignment means 34 and utilizing the repulsive force of an elastic body 32, by which the uneven thickness is regulated. A primary coating resin is supplied to a primary coating resin reserving chamber 22 from a resin supply passage 23 in the state of the end of the regulation and a secondary coating resin is supplied to a secondary coating resin reserving chamber 25 in the secondary coating die 17 from a resin supply passage 26, and the continuous operation to continuously produce the coated optical fiber by simultaneously coating the optical fiber with the primary coating resin and the secondary coating resin is started. If the uneven thickness is regulated in the manner described above, the degree of freedom of the aligned movement is increased, the regulation of the uneven thickness is facilitated and the occurrence of the uneven thickness may be prevented.