The present invention relates to nanomicelles composed of a complex of a lipophilic compound and a poly-gamma-glutamic acid wherein a portion of carboxyl groups are substituted with an amine group, and more particularly, to nanomicelles composed of a complex of a lipophilic compound and a poly-gamma-glutamic acid wherein a portion of carboxyl groups are substituted with an amine group, a preparation method thereof, and a drug delivery system employing the mucous membrane-adhesive property of the nanomicelles. According to the present invention, the nanomicelle drug delivery system based on poly-gamma-glutamic acid that is a natural biopolymer can be used for the delivery of a drug to mucous membranes to thereby increase the in vivo stability and effectiveness of the drug.