The present invention relates to a parenteral bioactive substance delivery composition and a bioactive substance carrier using a micelle based on low molecular weight methyl cellulose with a weight average molecular weight of 6 to 9.5 kDa. The bioactive substance carrier according to the present invention can completely resolve a problem of excretion to outside the body which cannot be resolved by conventional low molecular weight methyl cellulose having a weight average molecular weight of 10 to 20 kDa to increase safety and form a micelle to enable the solubilization of poorly soluble drugs, and thus is expected to be very useful for sustained release parenteral drug delivery.
