To provide a cleaning agent comprising a sheet of natural charcoal in contrast with conventional chemical detergent and, accordingly, good for the environment and safely usable for babies and atopic persons.

A charcoal sheet is covered with a cloth or mesh having fine mesh size to prevent the escape of the charcoal powder and is put into a wash tub together with the clothes to be cleaned. The clothes are washed in a state entangled with the charcoal sheet floating on the water surface. The sheet is safely usable in an automatic washing machine fundamentally different from the conventional attempt to put a Bincho-tan (a kind of high-quality charcoal) in a stocking, etc., and suspending on the wall of the wash tub. A large-sized charcoal sheet can be used for the softening of bathing water by putting in a bathtub.