A mass-producible lithium ion capacitor that allows lithium ions to be easily occluded by a negative electrode in advance is provided. A layered member includes: two copper foils each having a portion in which tabs are formed on one side along the longitudinal direction of the copper foils, and a portion in which a large number of through holes are formed and which is disposed adjacent to the portion with the tabs, and lithium metal having a thin plate shape and sandwiched between the copper foils to contact the portions with the through holes of the copper foils. The tabs are joined to a negative current collector ring, and electrically connected to a negative current collecting member. By leaving the layered member to stand for a predetermined period, it is possible to cause lithium ions to be occluded by a negative active material of the lithium ion capacitor.