Panax ginseng Meyer has been used for the treatment of immune diseases and for strengthening the immune function. In this study, we evaluated the innate immune-stimulating functions and action mechanisms of white ginseng (WG) and heat-processed ginseng (HPG) in RAW264.7 cells. According to LC-MS analysis results, WG contained typical ginsenosides, such as Rb1, Rc, Rb2, Rd, and Rg1, whereas HPG contained Rg3, Rk1, and Rg5 as well as typical ginsenosides. HPG, not WG, enhanced NF-κB transcriptional activity, cytokine production (IL-6 and TNF-α), and MHC class I and II expression in RAW264.7 cells. In addition, HPG phosphorylated MAPKs and NF-kB pathways. In experiments with inhibitors, the ERK inhibitor completely suppressed the effect of HPG on IL-6 and TNF-α production. HPG-induced c-Jun activation was suppressed by an ERK inhibitor and partially suppressed by JNK, p38, and IκBα inhibitors. Collectively, these results suggested that HPG containing Rg3, Rg5, and Rk1 increased macrophage activation which was regulated by the ERK/c-Jun pathway in RAW264.7 cells.