To make the most of a slidingly movable characteristic of polyacetal, and reduce a driving sound by constituting a resinous gear of a mixture of the polyacetal and a semi-aromatic liquid crystal polymer.

A resin-made gear is constituted of a mixture of polyacetal and a semi-aromatic liquid crystal polymer being liquid crystal polyester composed of a p-hydroxybenzoic acid residue unit and an ethylene terephthalate unit. A mixing rate of the polyacetal and the liquid crystal polymer is set to 95/5 to 60/40 in the weight ratio. When a rate of the liquid crystal polymer is less than this, an effect to reduce a driving sound of a gear is not sufficiently exhibited, and when it is too much, a creep characteristic gets worse, and since an excellent characteristic of the polyacetal is impaired and an expensive liquid crystal polymer is used in large quantities, a cost is increased. When the polyacetal and the liquid crystal polymer are molded by a material pelletized by previously kneading both resins by a kneader such as an extruder, the liquid crystal polymer is uniformly dispersed in the polyacetal, and molding is stabilized.