4-Azaindole derivatives which are modulators of muscarinic acetylcholine receptor (mAChR) M1 and which may be effective for the prevention or disease modifying or symptomatic treatment of cognitive deficits associated with neurological disorders such as Alzheimer-type dementia (AD) or dementia with Lewy bodies (DLB), and a pharmaceutical composition comprising a 4-azaindole derivative as an active ingredient.