A steering wheel body 1 comprises sheaths 7a, 7b which covers a ring core bar 5 and spoke core bars 6A-6C, and a pad 3 formed integrally with the sheaths. A boss 8, 51, 28 is integral with the spoke core bars. A steering shaft 30 is formed at a distal end thereof with a serration 31 and an annular groove 32. The boss 8, 51, 28 includes a boss plate 33, a cylindrical portion 34, 74 with a serration 38, 68, 78, and a yoke portion 35 with through holes 36, 37, 66, 67, 76, 77. The cylindrical portion 34, 64, 74 is fitted on the end of the steering shaft 30 such that the serrations 31, 38, 68, 78 mesh with each other, and a bolt 41, 81, 91 is inserted and screwed into the through holes 36, 37, 66, 67, 76, 77. A collar 47 fitted on the bolt 41, 81, 91 is fitted in the annular groove 32. Strain stress is never transmitted directly to the bolt 41, 81, 91. The boss 8, 51, 28 comprises a boss body 66 composed of the cylindrical portion 34, 64, 74 and the yoke portion 35, 65, 75, and the boss plate 33 fixed by welding to the boss body. When casting the spoke core bars 6A-6C from aluminum, the boss plate 33, 53 serves as a seal in a die so that molten aluminum is prevented from going around to the inside of the cylindrical portion 34, 64, 74 through an opening of the yoke portion 35, 65, 75, and therefore the extreme edge of the boss plate 33, 53 can be embedded in the spoke core bars 6A-6C.