Method of producing biosoluble inorganic fiber

A method of producing inorganic fibers comprising:

• Heating and melting an inorganic raw material that comprises 70 wt % or more of silica and 10 wt % to 30 wt % of magnesia and calcia in total in a container to obtain a melt having a melt viscosity of 15 poise or less,
• supplying the melt to a rotor that rotates at an acceleration of 70 km/s2 or more,
• drawing the melt due to a centrifugal force caused by rotation of the rotor to obtain fibers,
• blowing the fibers off by blowing air around the rotor, and
• collecting the fibers to obtain fibers having an average fiber diameter of 5 μm or less,
• wherein the container has a hole for supplying the melt to the rotor at its bottom, a rod is provided inside the container toward the hole, and the amount of the melt supplied to the rotor is adjusted by bringing the rod close to the hole when the hole has increased in diameter, and
• wherein the melt viscosity of the melt and the acceleration of the rotor satisfy the following expressions,
• A≧36.81×P−11.21, and
• 15≧P
• where, P is the melt viscosity (poise) of the melt, and A is the acceleration (km/s2) of the rotor.