A carbon/carbon composite is prepared without using any expensive carbon fiber fabric and without performing any complicated molding step prior to a densifying step. More specifically, a pitch-based infusiblized fiber alone, or optionally in the form of a mixture thereof with a pitch-based carbonized fiber, is subjected to carbonization and molding under uniaxial pressing to obtain a carbon/carbon composite preform. The preform is then densified using a carbonaceous matrix.