An optical fiber production method comprising: a drawing process of drawing an optical fiber preform in a drawing furnace; and a slow cooling process of slowly cooling an optical fiber drawn in the drawing process, wherein in the slow cooling process, the optical fiber is passed through a plurality of annealing furnaces, using Equation below, a temperature T of glass constituting a core included in the optical fiber, at which a fictive temperature of the glass can be most efficiently decreased, is determined, and then using the temperature T, an upper limit and a lower limit of a temperature difference between a temperature of the optical fiber and the fictive temperature of the glass, at which an increase is less than 0.001 dB/km with respect to a transmission loss of the optical fiber when the fictive temperature of the glass is most efficiently decreased, are calculated, and in the slow cooling process, temperatures of the annealing furnaces are set such that the temperature difference is within a range from the upper limit to the lower limit. T = − E act k B + E act k B 2 + 4 E act k B T f 2 (In Equation above, E act is activation energy of the glass, k B is Boltzmann constant, and T f is the fictive temperature of the glass, wherein Equation below is held in a given period in the slow cooling process, where a time constant of relaxation of a structure of glass forming a core included in the optical fiber is defined as τ(T), a temperature of the optical fiber at a point in time in the slow cooling process is defined as T, a fictive temperature of glass forming the core at the point in time is defined as T f 0 , and a fictive temperature of glass forming the core after a lapse of time Δt from the point in time is defined as T f 20 ° C < T f − T = T f O − T exp − Δ t / τ T < 100 ° C a drawing process of drawing an optical fiber preform in a drawing furnace; and a slow cooling process of slowly cooling an optical fiber drawn in the drawing process, wherein in the slow cooling process, the optical fiber is passed through a plurality of annealing furnaces, using Equation below, a temperature T of glass constituting a core included in the optical fiber, at which a fictive temperature of the glass can be most efficiently decreased, is determined, and then using the temperature T, an upper limit and a lower limit of a temperature difference between a temperature of the optical fiber and the fictive temperature of the glass, at which an increase is less than 0.001 dB/km with respect to a transmission loss of the optical fiber when the fictive temperature of the glass is most efficiently decreased, are calculated, and in the slow cooling process, temperatures of the annealing furnaces are set such that the temperature difference is within a range from the upper limit to the lower limit. T = − E act k B + E act k B 2 + 4 E act k B T f 2 (In Equation above, E act is activation energy of the glass, k B is Boltzmann constant, and T f is the fictive temperature of the glass, wherein Equation below is held in a given period in the slow cooling process, where a time constant of relaxation of a structure of glass forming a core included in the optical fiber is defined as τ(T), a temperature of the optical fiber at a point in time in the slow cooling process is defined as T, a fictive temperature of glass forming the core at the point in time is defined as T f 0 , and a fictive temperature of glass forming the core after a lapse of time Δt from the point in time is defined as T f 20 ° C < T f − T = T f O − T exp − Δ t / τ T < 100 ° C <EOS>