PROBLEM TO BE SOLVED: To provide a stairs baseboard member, which can be easily mounted without any laborious work. SOLUTION: A baseboard member 1 mounted in a boundary part between a tread face or a riser face of wooden stairs and a side wall is longer than a baseboard for one step of the stairs and is provided with a required width. In the edge part, which is provided flexibility, of this baseboard member, a notch part matching with a step tread face point part shape is previously arranged in the position corresponding to the step tread point part. As a material for the baseboard member 1, a material, in which desirably designed soft resin/ paper sheet is stuck to the surface and the edge part of a synthetic wood molded into a desired dimension of the baseboard in an outline, or a molded material made of soft resin as a whole is used.