An electric wire connection structure is composed of insulated electric wires each including a core and an insulation coating covering the core. The cores of the insulated electric wires are connected to pads provided on a substrate. The insulated electric wires are arranged along a predetermined alignment direction and arranged parallel to each other. The insulation coating is removed at a part in a longitudinal direction of each of the insulated electric wires to expose the core. Exposed portions of the cores are connected to the pads, respectively. Some of the insulated electric wires are configured in such a manner that the core is exposed in an area where the insulation coatings of adjacent ones of the other insulated electric wires in the alignment direction are not removed.