In a switch module which is arranged in opposition to a key substrate, the switch module is provided which is able to reduce an amount of light leaking out from the vicinity of an end of a light guiding member in the direction of key parts, so that the key parts can be illuminated in a uniform manner by the light which advances in the interior of the light guiding member. A switch module (1) is provided with a circuit substrate (6) that has a metal dome sheet (4) mounted on a surface thereof which is arranged in opposition to a key substrate (8), a light guiding sheet (4) that is arranged between the key substrate (8) and the circuit substrate (6), an LED (2), and a reflector (9) that makes the light emitted from the LED (2) incident into the light guiding sheet (3) from an end thereof, wherein key parts (7) are able to be illuminated by the switch module (1). The light guiding sheet (3) has a first surface (3b) that is arranged in opposition to the key substrate (8), and a second surface (3c) that is arranged at an opposite side of the first surface so as to be in opposition to the circuit substrate (6). In the vicinity of an end in the second surface (3c), there is formed a print pattern (12) by black ink on an optical path of the light which, after being reflected on the second surface (3c), transmits through the first surface (3b) in the vicinity of an end thereof, without being reflected on the first surface (3b).