A tire component is fabricated by the steps of forming a narrow belt by arranging a plurality of cords and embedding the cords in a rubber layer, cutting the belt into strips of a predetermined length, and successively arranging and joining a necessary number of the strips such that edge parts of adjacent strips overlap each other with the outermost cord in the edge part of one of the adjacent strips overlying the outermost cord in the edge part of the other strip. The strips can be surely joined without requiring advanced techniques, without wasting materials and without increasing weight. Thus a desired annular tire component can be accurately formed in a desired circumference. The cords are arranged in each strip in a width equal to a length shorter than a length equal to an integral division of the predetermined circumference of a tire by a length corresponding to an increase in the diameter of the tire component. A tire component of a predetermined circumference can be accurately formed by increasing the diameter of an annular ply fabricated by successively joining an integral number of the strips such that the edge parts of the adjacent strips overlap each other with the outermost cord in the edge part of one of the adjacent strips superposed on the outermost cord in the edge part of the other strip. A pneumatic tire including the thus formed carcass ply thus fabricated has an improved quality.