To provide a gear manufacturing method capable of obtaining strength improvement effect of a tooth flank, and a gear.

A gear manufacturing method includes a gear forming process for forming a gear and a surface modification treatment process for applying surface modification treatment to a tooth flank of the gear. In the surface modification treatment process, surface modification treatment is applied so that magnitude of compression residual stress on an outermost surface of the tooth flank is 800 MPa or more, maximum height roughness Rz of the tooth flank is 4 μm or below, and a protruded peak part height Rpk of the tooth flank is 0.40 μm or more. According to the gear manufacturing method, a gear with teeth flanks having excellent conformability without causing micro cracks on the surface in a process of adaptive wear can be manufactured while properly wearing in an operation initial stage, and thus enhancing effect of the tooth flank strength can be obtained which is sufficiently higher compared with conventional ones.