An object of the present invention is to provide asolid composition comprising a stabilized salt ofaminocarboxylic acid. The object can be attained by apharmaceutical solid composition comprising [(1R,5S,6S)-6-(aminomethyl)-3-ethylbicyclo[3.2A]hept-3-en-6-yl]acetic acid monobenzenesulfonate which is compoundrepresented by the following formula (I) in combinationwith appropriate additives.(See Formula I)