Backlight module capable of avoiding light leakage

A keyboard capable of avoiding light leakage, comprising:

• a circuit board;
• a plurality of keys connected to one side of the circuit board;
• and
• a backlight module comprising:
• a substrate disposed on another side of the circuit board;
• a shading film having a first surface and a second surface opposite to each other, wherein the shading film forms a first hole penetrating the first surface and the second surface, and the shading film is connected with the substrate via the first surface;
• a light guide plate connected to the second surface, wherein the light guide plate forms a second hole corresponding to the first hole while the aperture of the second hole is greater than that of the first hole, a side of the shading film near the first hole has an extending section while a side of the shading film near the second hole does not, and a first shading portion is disposed on the extending section of the shading film;
• a light-emitting element disposed on a light entering side of the light guide plate;
• and
• a reflective sheet connected to a side of the light guide plate, wherein the reflective sheet forms a third hole corresponding to the second hole while the aperture of the third hole is greater than that of the second hole, a side of the reflective sheet near the third hole has an adhesive section while a side of the light guide plate near the second hole does not, the adhesive section is connected with the extending section and covers a side of the light guide plate near the second hole, for preventing light generated from the light-emitting element from exiting through the second hole.