This study evaluated cholineresterase inhibitory activity of Korean white ginseng extract (WGE), red ginseng extract (RGE), and black ginseng extract (BGE) and the cholinergic effect on scopolamine (SCOP)-induced amnesic mice. WGE, RGE, and BGE inhibited acetylcholineserase (AChE), as well as butyrylcholineserase (BuChE) in a concentration-dependent manner. BGE presented strong inhibition of AChE with an $IC_{50}$ value of 1.72 mg/mL, followed by WGE (5.89 mg/mL), RGE (6.30 mg/mL), respectively. The inhibitory activity of the three ginseng extracts on BuChE showed similar values among the groups. To better understand the mechanisms of the possible effect of ginseng extract on the cholinergic function, this study assessed the expression of the cholinergic markers of choline acetyltransferase (ChAT) and AChE using western blot and RT-PCR analysis in the brains of amnesic mice. Treatment with ginseng extracts led to inhibition of AChE expression and, the activation of ChAT expression in the hippocampus and the cerebral cortex of amnesic mice as induced by SCOP. The results suggest that ginseng extracts including BGE, appear to modulate the metabolism of acetylchoine (ACh), which would greatly increase synaptic ACh levels and most potently revert SCOP-induced amnesia.