In order to define the ablation phenomena of the inorganic fiber reinforced ablative materials, the chop type specimen and the laminate one of phenol resin matrix composites have been reinforced with carbon, silica and glass fiber, respectively, were made and examined by the oxy- acetylene torch testing method for 110 seconds. The ablation phenomena, the microstructural change by the internal stress were studied. And both the backface temperature and the weight decrease were measured with the ablation time. Results obtained are as follows. Char layer of the ablative materials is being grown by the repeated actions of melting, decomposing and vaporizing and it is porous at surface region but dense inner the surface one. The deposition of carbon originated from the decomposition of vaporized gases was occured at the surface and resulted in formation of hard layer. Back face temperature of the ablative materials was ordered as follows, carbon-phenolic>glass-phenolic>silica-phenolic. Though the back face temperature of the laminate type was higer than that of the chop type, the thermal resistance of the laminate type is thought to be superior to that of the chop type as materials for high temperature ablation.