The objective of this study was to investigate the anticancer effects of EMPS (edible mushroom mycelium polysaccharide: Tremella fuciformis) in animal models with colorectal cancer induced by AOM/DSS. The experimental groups consisted of Nor (normal), NC (AOM/DSS), EMPS (EMPS 50, EMPS 100), and PC (Fluorouracil). The NC group had the highest number of colon tumors, whereas it was observed that tumor occurrence was significantly reduced in the EMPS consumption group. The expression of Bcl-2, an apoptosis inhibitor, was significantly lower in the EMPS 50 & 100 and PC groups. On the other hand, the mRNA gene expression of Bax, a factor that induces apoptosis, was significantly higher in the EMPS 50 & 100 and PC groups compared to the NC group. The mRNA expression levels of TNF-α and COX-2 significantly increased in the NC group, but showed a significant decrease in the EMPS and PC groups, indicating inhibition of the cancer-promoting response of cells. At the phylum level of the mice's intestinal microbial composition, the proportion of Bacteroidetes tended to decrease, while the proportion of Firmicutes tended to increase with EMPS administration. This suggests that changes in the gut microbiota caused by inflammation can be influenced by dietary intake.