We explore a question of whether quark Pauli principle plays an important role or not in the binding mechanism of &Lgr; hypernuclei. We introduce a special five-baryon configuration which is forbidden by the Pauli principle at the quark level. By excluding the forbidden state, we show that the &Lgr; separation energy of&Lgr;5Heor&Lgr;&Lgr;6Heis significantly reduced for a baryon size of 0.86 fm, while it is unchanged for a smaller size of 0.6 fm. We also show a qualitative estimation of the energy reduction for more heavier systems,&Lgr;9Beand&Lgr;&Lgr;10Be,by an &agr; cluster model. ©2001 American Institute of Physics.