A method of producing an optical fiber that includes: a core ; a cladding layer that is lower in refractive index than the core ; and a depressed layer that lies between the core and the cladding layer and that is lower in refractive index than the cladding layer , the optical fiber having a propagation constant difference Δβ equal to or greater than a predetermined value Δβ0 [rad/m], the propagation constant difference Δβ referring to a difference between a propagation constant of a propagation mode and a propagation constant of a radiation mode, the method comprising: a first step of determining a refractive index profile of the optical fiber such that: (a) an effective core area Aeff at a wavelength of 1.55 pm of the optical fiber is equal to or greater than 100 [μm 2 ] and equal to or less than (16650 [rad/m] - Δβ0 [rad/m]) / 63.2 [(rad/m)·(1/μm 2 )]; (b) a radius r1 of the core is equal to or greater than (9329 [rad/m] + Δβ0 [rad/m]) / 3429 [(rad/m)/μm] and equal to or less than (21180 [rad/m] - Δβ0 [rad/m]) / 1714 [(rad/m)/pm]; (c) a refractive index volume Vcore of the core is equal to or greater than (-655 [rad/m] + Δβ0 [rad/m]) / 923 [(rad/m)/(%μm 2 )] and equal to or less than (16420 [rad/m] - Δβ0 [rad/m]) / 480 [(rad/m)/(%μm 2 )]; and (d) a refractive index volume Vdep of the depressed layer is equal to or greater than (-13300 [rad/m] + Δβ0 [rad/m]) / 120 [(rad/m)/(%μm 2 )] and less than 0 [%μm 2 ]: and a second step of producing an optical fiber having the refractive index profile determined by the first step. a first step of determining a refractive index profile of the optical fiber such that: (a) an effective core area Aeff at a wavelength of 1.55 pm of the optical fiber is equal to or greater than 100 [μm 2 ] and equal to or less than (16650 [rad/m] - Δβ0 [rad/m]) / 63.2 [(rad/m)·(1/μm 2 )]; (b) a radius r1 of the core is equal to or greater than (9329 [rad/m] + Δβ0 [rad/m]) / 3429 [(rad/m)/μm] and equal to or less than (21180 [rad/m] - Δβ0 [rad/m]) / 1714 [(rad/m)/pm]; (c) a refractive index volume Vcore of the core is equal to or greater than (-655 [rad/m] + Δβ0 [rad/m]) / 923 [(rad/m)/(%μm 2 )] and equal to or less than (16420 [rad/m] - Δβ0 [rad/m]) / 480 [(rad/m)/(%μm 2 )]; and (d) a refractive index volume Vdep of the depressed layer is equal to or greater than (-13300 [rad/m] + Δβ0 [rad/m]) / 120 [(rad/m)/(%μm 2 )] and less than 0 [%μm 2 ]: and (a) an effective core area Aeff at a wavelength of 1.55 pm of the optical fiber is equal to or greater than 100 [μm 2 ] and equal to or less than (16650 [rad/m] - Δβ0 [rad/m]) / 63.2 [(rad/m)·(1/μm 2 )]; (b) a radius r1 of the core is equal to or greater than (9329 [rad/m] + Δβ0 [rad/m]) / 3429 [(rad/m)/μm] and equal to or less than (21180 [rad/m] - Δβ0 [rad/m]) / 1714 [(rad/m)/pm]; (c) a refractive index volume Vcore of the core is equal to or greater than (-655 [rad/m] + Δβ0 [rad/m]) / 923 [(rad/m)/(%μm 2 )] and equal to or less than (16420 [rad/m] - Δβ0 [rad/m]) / 480 [(rad/m)/(%μm 2 )]; and (d) a refractive index volume Vdep of the depressed layer is equal to or greater than (-13300 [rad/m] + Δβ0 [rad/m]) / 120 [(rad/m)/(%μm 2 )] and less than 0 [%μm 2 ]: and a second step of producing an optical fiber having the refractive index profile determined by the first step. <EOS>