<p>The purpose of this study is to examine the influence of soil microbes on the degradation of pipe-shaped red iron oxide pigments. Since there are differences between the conditions of samples for observation and those for analysis in this study, two kinds of culture examinations were performed for the observation and identification of particles. In the culture examination for observation of particles, the pipe-shaped red iron oxide material was annealed to form pipe-shaped particles, which were used as culture samples. The culture samples and iron-reducing bacteria were placed in a liquid medium and cultivated. After cultivation, the particle shape and hue of the samples were observed using a digital microscope and a scanning electron microscope. In the culture examination for crystal identification, annealed and crushed pipe-shaped red iron oxide material was used. The particle samples and iron-reducing bacteria were placed in a liquid medium and cultivated. After cultivation, the samples were subjected to X-ray analysis for crystal identification. This study allowed obtaining information about the changes in shape of pipe-shaped red iron oxides under the influence of iron-reducing bacteria.</p>