A multipole lens producing less magnetic field variations is offered. Also, a charged-particle beam instrument fitted with such multipole lenses is offered. The multipole lens has plural polar elements, an annular holding member, and an annular yoke disposed outside the holding member. Each polar element has a held portion and a base-end portion. The held portions of the polar elements are held by the holding member. The yoke is magnetically coupled to the base-end portions of the polar elements. The yoke is provided with openings extending circumferentially. The base-end portions of the polar elements are positioned in the openings.