In order to estimate dependence of volume fraction of ceramic and metallic phase on composite's creep behavior, we fabricated Ti-TiB in situ composites whose volume fractions of TiB were 10, 24 and 40%. The steady-state creep rates of all composites were agreement with the estimation of continuum mechanic. Microstructure of Ti-40TiB, however is quite different from that of Ti-10TiB, because TiB whiskers are strongly connected each other in Ti-40TiB. This structure of Ti-40TiB seems to require the deformation off TiB to creep, and of creep behavior of composites with high volume fraction of reinforcements requires more extensive study.