The present invention discloses an illumination device for an electronic device. The electronic device has a screen and a host, wherein a first lateral side of the screen is pivotally connected to the host having a keyboard surface. The illumination device includes a lampshade, a clamping portion and a light source. The clamping portion is connected to the lampshade and clamps the illumination device on a second lateral side of the screen, wherein the second lateral side is an opposite side of the first lateral side. The light source is disposed in the lampshade and provides an illuminating light, wherein a fixed angle is formed between an optical axis of the illuminating light and a keyboard surface of the host.