A clamp lamp uses two clamping parts to clamp an outer casing of a monitor stably. In an embodiment, the clamp lamp also uses a C-shaped resilient clip for convenience of clamping a light source thereof. In another embodiment, the clamp lamp also uses a C-shaped resilient clip for convenience of clamping a light source thereof, and a resilient part for assisting the clamping. In another embodiment, the clamp lamp also uses the two clamping parts to clamp the outer casing by touching front and rear surfaces of the outer casing simultaneously; therein, the portion of one clamping part that touches the front surface is shorter than the portion of the other clamping part that touches the rear surface.