To provide a manufacturing method of a bent bar stock by which bending is stably and easily done while reducing a thickness decrease on a bending outer peripheral side or adding to the thickness thereof.

The bar stock 1 to be bent is held by an arm side clamp 3 and an intermediate clamp 13, a desired region of the bar stock 1 is thickened by applying compression force with a pressing apparatus 12 while moving a heating apparatus 17 along the bar stock 1, afterward, at the state the heating apparatus 17 is held at a prescribed position, the bar stock 1 is advance by the pressing apparatus 12, by turning a bending arm 2, bending is applied to the region previously thickened.