The present invention provides a copolymer used as oily gelling agent with which a stable oily gelled composition can be prepared.The copolymer of the present invention is characterized by comprising a hydrophobic monomer represented by the following general formula (1) and a hydrophilic monomer represented by the following general formula (2) and/or the following general formula (3).(In formula (1), R1 is a straight-chain or branched-chain alkyl group having 16 to 22 carbon atoms. R2 is a hydrogen atom or a methyl group.)(In formula (2), R3 is a hydrogen atom, a glyceryl group, a straight-chain or branched-chain hydroxyalkyl group having 1 to 4 carbon atoms, or a polypropylene glycol group represented by —(C3H6O)nH (here, n is an integer of 2 to 10). R4 is a hydrogen atom or a methyl group.)(In formula (3), R5 is a hydrogen atom or a methyl group, R6 is a straight-chain or branched-chain alkyl group or hydroxyalkyl group having 1 to 4 carbon atoms, or a substituent represented by the following structural formula (4).)
