To provide a preform for a photonic band gap fiber, capable of producing a photonic band gap fiber capable of suppressing the transmission loss of light.

The preform for a photonic band gap fiber is produced by a method comprised of the following processes: a formation process for continuously forming a columnar core glass body 10 used as the core of an optical fiber and a clad glass body 20 being a clad of an optical fiber and covering the core glass body, thus forming an intermediate base material 110; a hole-forming process for forming a hole 30 on the clad glass body 20 in the longitudinal direction of the core glass body 10; an inserting process for inserting, into the hole 30, a double-layer glass rod 40 obtained by covering a high refractive index section 41 having a refractive index higher than that of the clad glass body 20 with an outside layer 42 having a refractive index equal to that of the clad glass body; and a heating process for uniting the intermediate preform 110 and the double-layer glass rod 40 by heating the intermediate preform 110 formed by inserting the double-layer glass rod 40 into the hole 30.