To apply a cosmetic over the whole length of the eyelash by providing a long-length cross-section in the direction of a longest axis which is at least a part of a brush envelope surface and is orthogonal to a curvature surface in a brush being suitable as a make-up utensil having a bent core part.

In a brush material, the long-length core part 112 is force-fed and fixed to the end part of a straight bar shape part for deciding a main axis X-X and stiff hair s radically fitted in the helical winding part of the core part 112. The end part of stiff hair demarcates the surface of the brush material. The surface is a rugby ball-shaped projecting and symmetrical one and its end parts are two disk parts. Almost flat parallel surfaces 119 are formed over the whole length of the brush material, the cross-section of then brush material in the surface being horizontal to X-X is adopted as an almost rectangular curved line 115c in notched areas of the surfaces 119 and it is set to provide long axis length D in a longest axis Z-Z direction and max. width d(D>1.5d) along a max. width axis Y-Y direction.