To provide an emulsifier or compatibilizer for wax which has good biodegradability and does not adversely affect the environment and to provide an aqueous wax composition containing the same.

This emulsifier or compatibilizer comprises a compound represented by formula (1) (R1 is H, a 1-4C alkyl, or a 2-4C hydroxyalkyl; R2 and R3 are each a 1-4C alkyl, a 2-4C hydroxyalkyl, or -R5OCOR6; R4 is -R5OCOR 6; R5 is an alkylene; R6 is a fatty acid residue; and X is an anionic atom or an anionic group). The aqueous wax composition contains the emulsifier or compatibilizer.