The apoptotic effect of bacteria-derived $eta$-glucan was investigated in human colon cancer cells SNU-C4 using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay, reverse transcription-polymerase chain reaction (RT-PCR) expressions of Bcl-2, Bax, and Caspase-3 genes, and assay of caspase-3 enzyme activity. $eta$-Glucan of 10, 50, and $100{mu}g$/mL decreased cell viability in a dose-dependent manner with typical apoptotic characteristics, such as morphological changes of chromatin condensation and apoptotic body formation from TUNEL assay. In addition, $eta$-glucan ($100{mu}g$/mL) decreased the expression of Bc1-2 by 0.6 times, whereas the expression of Bax and Caspase-3 were increased by 3.1 and 2.3 times, respectively, compared to untreated control group. Furthermore, the caspase-3 activity in the $eta$-glucan-treated group was significantly increased compared to those in control group (P < 0.05). Bacterial derived $eta$-glucan could be used as an effective compound inducing apoptosis in human colon cancer.