An object of the present invention is to provide a protective agent for a neuronal cell. The protective agent for a neuronal cell according to the present invention contains a compound represented by the following general formula [I] or a salt thereof as an active ingredient. In the formula, R.sub.1, R.sub.2 and R.sub.3 are the same or different and represent a hydrogen atom or an alkyl group, or R.sub.1 and R.sub.3 may be joined together to form a ring having one or more double bonds. ##STR00001##