As the hydrophobic polymer chain segment is directed inside, it contains with the electric charge lipid which has the electric charge which is opposite to the block copolymer unit and the electric charge when the hydrophilic polymer chain segment is directed outside is laid out in radial pattern of the medicine which it should contain it makes the grain constituent which is laid out when it can draw to hydrophobic polymer chain segment side the particular electric charge lipid. With this grain constituent, although the medicine containment inside the grain by the capacitive coupling with the electric charge lipid the grain peripheral face having the electric charge which can induce the electrification Characteristic material which has the electric charge which is opposite to the electric charge lipid is prevented.疎水性ポリマー鎖セグメントを内側に向けると共に親水性ポリマー鎖セグメントを外側に向けた状態で放射状に配置されたブロックコポリマーユニットと、内包されるべき薬物の電荷とは反対の電荷を帯びた荷電脂質とを含有し、当該荷電脂質が疎水性ポリマー鎖セグメント側に引き寄せられた状態で配置された粒子組成物とする。この粒子組成物では、荷電脂質との静電結合によって薬物が粒子内に保持される一方、荷電脂質とは反対の電荷を帯びた帯電性物質を誘引し得る電荷を粒子外周面が帯びることが防止される。
