An illumination device for tool (e.g., screw driver) includes a housing comprising a battery compartment an inverted V-shaped cavity on an underside, two opposite slit projections on a bottom edge, and a cover including a flat on a circumferential surface; a strap having one end hingedly secured to one projection and comprising a hook and loop fabric fastener at the other end; first, second, and third magnetic members on the housing; and a light emitting assembly mounted in the housing and comprising two LEDs projecting out of the housing. A screw driver can be disposed in the inverted V-shaped cavity and adhered to the first magnetic members such that causing the strap to support the screw driver from below and wrapping the strap around the other projection to secure to the hook and loop fabric fastener will secure the screw driver and the housing together.