The invention can reduce a step between rubber strips even in the case that the rubber strip is made thick, and inhibits a reduction of uniformity and tire quality, a deterioration of a tire outer appearance, and the like. A rubber strip (10) may be scalene triangular shape, a trapezoidal shape or a parallelogram shape having has a bottom line (11) forming a strip width (W), a first diagonal line (12) extending from one end of the bottom line (11) and a second diagonal line (13) extending from the other end (P2) of the bottom line (11), a length (L0) of the bottom line is set to 5 to 50 mm, and a thickness (T) thereof is set to 0.2 to 5.0 mm.