A shaft has a weight of 50 g or less. A forward flex is 110 mm or less. A backward flex is 100 mm or less. A shaft torque is 4.0° to 6.5°. The shaft includes a first hoop layer, a second hoop layer longer than the first hoop layer, and a third hoop layer longer than the second hoop layer. An outer diameter at a position 550 mm apart from a tip end is D5. An outer diameter at a position 950 mm apart from the tip end is D9. A crushing strength at the position 550 mm apart from the tip end is F5. A crushing strength at the position 950 mm apart from the tip end is F9. F5/D5 is 1.5 or greater and 2.5 or less. F9/D9 is 1.0 or greater and 2.0 or less. A difference (F5−F9) is 4 kgf or less.