Abstract: A method for recognizing a press of a key by a small force on a slim portable keyboard for use with a smart phone, a tablet PC, a general PC, or a notebook computer. A special-key press processing unit processes a press of a plurality of special keys. A plurality of general-key press processing units process a press of a plurality of general keys. A set number of general keys are configured to be one block. The keyboard is slim and can be conveniently carried. The keyboard includes a plurality of special key resistances and a plurality of general key resistances, each of which is proportional to a pressure caused by a press, to recognize a press of a key even when the key is pressed by a small force.