A gear grasping device includes a main body, a first jaw, a second jaw, and an adjustment means. The main body is provided with a curved portion accompanied with an opening. The first jaw and the second jaw are disposed on the main body. The opening is arranged between the first jaw and the second jaw. By the adjustment means, position of the first jaw is changeable for adjusting a jaw span between the first jaw and the second jaw. Therefore, the gear grasping device is fit for sizes of gears, and is operation-friendly.