This study was designed to evaluate the protective effects of Dodamtanggami-bang (DDTG) on tunicamycin induced cell death by ER stress in C6 glial cells. Cell viability was measured by MTT assay and LDH release. Apoptosis was determined by caspase activity and flow cytometry in C6 glial cells. Expression of ER stress mediators including, GRP78 and CHOP proteins were measured by Western blot analysis. Tunicamycin induced the apoptosis of C6 glial cells, which was characterized as nucleic acid and caspase-3 activation, PARP cleavage, and sub-G0/G1 fraction of cell cycle increase. However, pretreatment with DDTG protected C6 glial cells from tunicamycin. Treatment with tunicamycin resulted in the increased the expression of GRP78 and CHOP protein and produced ROS generation. However, pretreatment with DDTG inhibited the ER stress pathway, including increase of the expression of GRP78, CHOP proteins in C6 glial cells treated with tunicamycin. Taken together, these data suggest that DDTG is able to protect C6 glial cells from tunicamycin with marked inhibition of ER stress.