The intestinal ecosystem is involved in the pathogenesis of mood disorders such as depression. Intestinal microbes can affect the central nervous system through the gut-brain axis, which raises the possibility of using probiotics for preventing depression. In this study, we examined the effect of heat-inactivated Lactobacillus gasseri CP2305 (CP2305) in a subchronic and mild social defeat stress (sCSDS) mouse model. sCSDS suppressed food intake. However, dietary CP2305 intake rescued it, suggesting that CP2305 improved the decreased appetite in sCSDS mice. sCSDS did not alter the gene expression of brain-derived neurotrophic factor, nerve growth factor, and neurotrophin-3 in the hippocampus. However, dietary CP2305 provided following sCSDS increased the gene expression of these neurotrophins in the hippocampus. These findings suggest that CP2305 supplementation would aid in preventing psychosocial stress-induced disorders.