A porous glass intermediate body constructed by a core original layer
formed as a core portion of an optical fiber, and a first clad original
layer formed as a first clad portion of the optical fiber is formed.
Thereafter, a transparent glass intermediate body is made by consolidating
the porous glass intermediate body within an atmospheric gas with a
chlorine-based gas with no fluorine compound. Thereafter, a porous optical
fiber base material is made by forming a second clad original layer as a
second clad portion of the optical fiber on the circumferential surface of
the transparent glass intermediate body. When a porous state is then
maintained, the porous optical fiber base material is dehydrated within
the atmospheric gas with a chlorine concentration higher than that during
the consolidation of the porous glass intermediate body. Thereafter, an
optical fiber base material is manufactured by consolidating the porous
optical fiber base material within a similar atmospheric gas. The optical
fiber is made by wire-drawing this optical fiber base material.
