Composite plain bearing, cradle guide, and sliding nut

A sliding nut that moves while axially sliding on a screw shaft in accompaniment with the rotation of the screw shaft in a sliding screw device, comprising a nut main body which comprises an ingot metal, wherein a resin layer of a resin composition in which a synthetic resin is used as a base resin is overlaid by injection molding as a threading groove part on a surface of a female threading part into which the screw shaft threadedly engages in the nut main body,

• a joining face of the nut main body having a joining film that chemically reacts with a resin layer on said joining face or a joining face of the nut body is provided with very small concavo-convex shapes,
• said female threading part is a portion of said nut main body and is formed in an inside diameter part of said nut main body,
• said resin layer, which is said threading groove part, is formed so as to cover said surface of said female threading part and
• said resin layer, which is said threading groove part, makes sliding contact directly with said screw shaft.