To provide a new multibranched macromolecular compound having a hydrophobic main chain and hydrophilic side chains, particularly having polymer micelle-forming ability.

The new multibranched macromolecular compound has, as the main chain, an epoxy compound skeleton composed of multifunctional glycidyl compound residue, monovalent aromatic hydroxy compound residue and bivalent aromatic hydroxy compound residue, and as side chains, hydrophilic straight-chain polymer chains each composed of such structural unit as of ethyleneimine, N-acylethyleneimine, propyleneimine, N-acylpropyleneimine, ethylene glycol or propylene glycol.