The intracerebral cholinergic system is important not only for cognitive function, but also for cerebral blood flow control. In patients with dementia, neuron loss is observed in the intracerebral cholinergic system, and cerebral cortical blood flow decreases. It has been reported that a Japanese medicine, ninjin’yoeito, improves cognitive decline in patients with Alzheimer’s disease, and activation of the intracerebral cholinergic system has been suggested as the mechanism. In this mini-review, we summarize current knowledge regarding cerebral blood flow control by the intracerebral cholinergic system and introduce our recent study on the effect of ninjin’yoeito on the resting cerebral cortical blood flow and the cerebral blood flow response to somatosensory stimulation.