PURPOSE: To obtain clean, safe and sanitary briquet with good ignitability by using a nitrocellulose soln. and/or a cellulose acetate soln. as a binder for a combustible solid material particle or as a coating agent for a molded material.

CONSTITUTION: A powdery combustible solid material such as charcoal or coal powder and an oxidizing agent such as potassium chlorate or permanganate are mixed, kneaded with addition of a nitrocellulose soln. (or a cellulose acetate soln.), such as a soln. of slow ignitor cotton of a low nitrogen content in acetone, and press molded into a desired form. Then the nitrocellulose soln. is applied to the surface of the obtd. molded material and dried to obtain a water- resistant briquet. It is possible to obtain briquet more excellent in water resistance by using wax such as ceresin wax in place of the nitrocellulose mixed as a binder with the powdery combustible solid material.