Incremental in-plane bending, which was developed by the authors, is a new flexible manufacturing technology for the small-lot production of sheet metals with various bending radii. A sheet metal is bent incrementally by inclined punch beating. Beating angle is an important factor of in-plane bending. The effects of beating angle on in-plane bending were investigated. Beating force, the distribution of thickness strain and bending radius were experimentally determined. It was clarified that beating angle is an important factor that affects bending radius. Moreover, deformation simulation was carried out and the effect of beating angle on the in-plane bending mechanism was compared with experimental result. It was found that there is a critical beating angle for obtaining the minimum bending radius for fixed indentation and width of sheet metals.