A button module including a cap, a first arm, a second arm, and a base is provided. The first arm has a first pivoting shaft, a first end connected to the cap, and a second end opposite to the first end. The second arm has a second pivoting shaft, a third end connected to the cap, and a fourth end opposite to the third end and pivoted to the second end. The first pivoting shaft and the second pivoting shaft are pivoted to the base respectively. A projection of the first pivoting shaft on the base is between a projection of the first end on the base and a projection of the second end on the base. A projection of the second pivoting shaft on the base is between a projection of the third end on the base and a projection of the fourth end on the base.