For the purpose of miniaturizing a zoom lens barrel, a zoom lens of the present invention comprises one lens group which moves at the time of variable power, one diaphragm member which moves at the time of variable power, and a cam member which has a cam section for a lens group, which guides the movement of the above-mentioned lens group at the time of variable power, and a cam section for a diaphragms which guides the movement of the above-mentioned diaphragm member at the time of variable power, wherein the above-mentioned cam section for a lens group and the above-mentioned cam section for a diaphragm are coupled.