Ninjinyoeito (NYT), a traditional Japanese medicine, is effective on physical strength, fatigue and anorexia. Recently, NYT ameliorated a cognitive dysfunction in patients with Alzheimer's disease (AD), however the mechanisms have been still unclear. In this study, we investigated the effects of NYT on spatial memory impairment in dementia model of rats. The dementia model of rats were prepared with transient cerebral ischemia and intraventricular injection of β-amyloid 1-42 for 7 days (CI+Aβ). NYT or donepezil were orally administered for 7 days after the cerebral ischemia. Spatial memory was evaluated using Morris water maze. We investigated the hippocampal and prefrontal cortical protein expression of α-amino-3-hydroxy-5-4-isoxazole propionic acid (AMPA) receptor subunit GluA1 and GluA2, Ca²⁺/calmodulin-dependant protein kinase Ⅱ (CaMKⅡ), and phosphor-CaMKⅡ. The treatment with NYT in the CI+Aβ rats shortened the extended time to reach the platform in Morris water maze, as well as donepezil treatment. Although NYT treatment did not ameliorate the decrease in GluA1 and GluA2 expression levels in hippocampus, NYT treatment showed the increase in GluA1 expression level and phoshor-CaMKⅡ/CaMKⅡ ratio in the prefrontal cortex of CI+Aβ rats. Therefore, NYT might improved spatial memory impairment via facilitation of glutamate signaling in the prefrontal cortex of the CI+Aβ rats. Our results suggest that NYT is a useful treatment for AD patients.