Cerebral nerve cell neogenesis agent

Disclosed are: a novel substance having a cerebral nerve cell neogenesis effect; and a cerebral nerve cell neogenesis agent which comprises the substance and is effective for the treatment and/or prevention of nerve diseases. Specifically disclosed is a cerebral nerve cell neogenesis agent comprising a plasmalogen as an active ingredient. Particularly, a cerebral nerve cell neogenesis agent comprising, as an active ingredient, a plasmalogen extracted from a biological tissue (preferably an avian tissue) that mainly contains ethanolamine plasmalogen and choline plasmalogen is preferred.