A wax applying device configured to apply wax to a traveling yarn includes: a casing including an attachment part for attaching the casing to a yarn winding device; a traverse guiding portion configured to guide the yarn to be wound by a winding unit of the yarn winding device so that the yarn is traversed forming a traverse area; and a wax support portion configured to support a wax body while the wax body is positioned in at least part of the traverse area. The traverse guiding portion is provided to the casing in a fixed manner, and the wax support portion is attached to the casing with a moving mechanism that is configured to be movable in a direction separating from the traverse area.