A wire holder is provided which allows for reduced number of process steps required in bundling wires. The wire holder is for relative alignment of a plurality of wires upon bundling the wires, and includes a plurality of wall portions formed rotationally symmetric to one another, provided to project in a direction orthogonal to an axis O serving as a rotation symmetry axis, and extending along the axis O. Between opposite ones of the wall portions, recesses each having an arc shape in cross section are formed to hold the wires. Each of the recesses has a span length of not less than 85% of the diameter of each of the wires. By fitting the wires into the recesses and arranging them along the rotation symmetry axis, the wires can be aligned.