Abstract: A keycap structure of a button includes a cap body, a plurality of clamping members and a covering member. The cap body is made of metal and has a first surface and a second surface. The covering member is disposed on the first surface. Each clamping member is connected to the second surface. A plurality of breaches is opened on the cap body, so that the breaches are disposed between the first surface and the second surface. Each breach is connected with each corresponding clamping member. Under this arrangement, since the cap body is made of metal, the thickness of the cap body is reduced while retaining mechanical strength; additionally, the total weight of the keycap structure of a button is reduced due to the breaches. Consequently, upon assembling the keycap structure of a button, a lighter and thinner keyboard or laptop is provided.