Novel 2,3-dihydro-1H-indene derivatives and salts thereof represented by the general formula (1), ##STR1## [wherein R.sup.1 and R.sup.2 are each a hydrogen atom, a lower alkyl group, a phenyl group which may have halogen atoms and/or alkyl groups as the substituents on the phenyl ring; R.sup.3 is a halogen atom or a lower alkyl group; R.sup.4 is a hydrogen atom, a halogen atom, a phenyl-lower alkyl group, a cycloalkyl-lower alkyl group or the like; R.sup.5 is a hydroxyimino group, an alkylamino group or a group of the formula --NHR.sup.8 (wherein R.sup.8 is a hydrogen atom, a halogen-substituted lower alkanoyl group or the like); R.sup.6 is a hydrogen atom or a phenyl group; and R.sup.7 is a hydrogen atom or a lower alkyl group].The 2,3-dihydro-1H-indene derivatives and salt thereof are useful as improving agents for treating anoxemic and hypoxic symptoms and syndromes accompanied therewith, cerebral activators, amnesia curative agents, presbyophrenia curative agents, treating agents for breathing arrest and improving agents for hypoxia accompanied with potassium cyanide poisoning, as well as useful as anti-inflammatory agents and hypotensive agents.