A button module includes a casing, a button body, an elastic body and a cover. The casing includes a first accommodating recess, a first engaging portion and a retaining platform. The button body is disposed in the first accommodating recess. The button body includes a first positioning portion. The elastic body is disposed between the button body and the retaining platform. The cover is disposed on the casing. The cover includes a second engaging portion, a second positioning portion and a retaining portion. The second engaging portion engages with the first engaging portion. The second positioning portion cooperates with the first positioning portion to position the button body in the first accommodating recess. The retaining portion abuts against the retaining platform.