A signal input module includes: a key body; a key base coupled to a lower portion of the key body, and having fixing portions of different heights at both sides thereof; a flexible printed circuit board disposed such that an upper surface thereof is covered by the key base, and having a dome portion on a rear surface thereof, the dome portion configured to generate a signal when pressed by the key base; and a light emitting portion formed on one surface of the flexible printed circuit board, wherein the fixing portion and the key base are connected to each other by a connection portion, wherein the connection portion is bent from one end of the key base, extends toward the fixing portion, wherein the connection portion is provided with a hole, and wherein the flexible printed circuit board is disposed to cross the hole. Under such configuration, the number of components can be reduced and the signal input module can have a slim configuration.