Avermectin derivatives represented by the general formula (I) or salts thereof: wherein -X----Y- represents -CH=CH-, -CH2-C(=O)-, -CH2-CH2-, or -CH2-CH(R13)- for example, 1) when -X----Y- represents -CH=CH-, R1 represents (R11)(R12)C [wherein R11 represents a substituted or unsubstituted lower alkyl group a formyl group a lower alkoxylcarbonyl group etc. and R12 represents a hydrogen atom or a lower alkyl group] when the bond between R2 and a carbon atom at the 5-position is a single bond, R2 represents a hydroxyl group or a tri(lower alkyl)silyloxy group or R2 forms a carbonyl group or a hydroxime group together with the carbon atom at the 5-position 2) when -X----Y- represents -CH2-C(=O)-, R1 represents (R11a)(R12a)C [wherein R11a represents a lower alkoxycarbonyl group, or -COOCH2CH=CH2 and R12a represents a hydrogen atom] and R2 represents a hydroxyl group or a tri(lower alkyl)silyloxy group.
