Abstract: A portable input device includes a support board, a plurality of key modules, a second input module, a cover, and at least one control unit. The support board has a first disposing region and a second disposing region. The key modules are located on the first disposing region of the support board. The cover covers the support board and has at least one opening. An accommodating space is defined by the cover and the second disposing region of the support board. The second input module is located in the accommodating space. The control unit is located in the accommodating space and electrically connected to the key modules and the second input module.