A porous optical fiber preform dehydration and sintering apparatus capable of improving the sealing performance between an upper lid and an elevating shaft and between the upper lid and a furnace tube or a furnace body, wherein an upper opening of a furnace tube for accommodating a porous optical fiber preform is shut by the upper lid, a preform holder is provided at the bottom end of an elevating shaft passing through the upper lid to be freely elevated therethrough, the porous optical fiber preform in the furnace tube is heated by a heater provided around the outer circumference of the furnace tube, the upper lid is formed by a metal, the preform holder is formed by a quartz glass or a ceramic, a corrosion-resistant layer is provided on an inner surface of the upper lid, a seal member made of rubber or resin is provided in an elevating shaft passage of the upper lid.