A foldable keyboard includes a main keyboard and a sub keyboard. The main keyboard includes a first edge, first keys, and a first housing on the first edge. The first housing defines a first recess with at least one inlet communicating with the first recess. The sub keyboard includes a second rotatably coupled to the first edge of the main keyboard, second keys, a second housing, a latching member, and at least one ejecting member. The second housing defines a second recess with at least one outlet and at least one cavity communicating with the second recess. The latching member is movably received in the second recess. The at least one ejecting member is respectively received in the at least one cavity and can be moved to eject the latching member out of the at least one outlet and into the at least one inlet of the main keyboard.