PURPOSE: To shorten the production time, make a material dense and use plural numbers of matrix materials by impregnating fine vacancies in fiber bundles and spaces among fiber bundles with matrix materials in separated processes and then finally, impregnating pores of a molded body with the matrix material.

CONSTITUTION: A fiber reinforce formed body 2 having about 50% porosity is produced by using fiber bundles 1 such as carbon fiber in such a manner that the fiber bundles are formed corresponding to the fiber shape (near net shape) by properly selecting uniaxially orientation or two- or three-dimensional orientation according to the product shape. In the first process of the production method, fine small vacancies 3 of about 10μm diameter among fibers are impregnated with mixture gas of methane and hydrogen as the source material to form films on the fiber surface by gas phase impregnating method (CVI) to form a matrix 4. In the second process, spaces 6 between fiber bundles 1 are impregnated with a liquid source material and baked. This procedure is repeated to form a matrix 7 which increases rigidity of the body. Then in the third process, pores 9 of fine cracking are impregnated with a matrix material 10 by CVI method.