To normally use in a combined state of a lighting system with a clock in a user's bedside for example, to inform time to a user even in the dark since the face of the clock is lightened with a part of light by lighting the lighting system, and to carry it in case of a disaster.

This portable lighting system with a detachable clock is composed of a square pillar-shaped lighting system body 1 having a light source, a light source battery, and a circuit for lighting, on the inside; and a notch in a part of the surface; and a clock 21 capable of attaching to and detaching from the notch. A light passage for taking out a part of light when the light source is lit is installed in a part of a partition constituting the notch of the lighting system body 1, and a light receiving window part 22 lightening the face 23 of the clock 21 by taking in a part of the light when the light source is lit and corresponding to the light passage when attached to the notch is installed in a part of a case in the detachable clock 21.