PURPOSE: To develop a gas purifying filter excellent in adsorbing property to various noxious substances, by forming dry Cyanophyta Spirillum, which is processed into a powdery form, into a granule alone or mixing the same with a powdery carrier before forming a granule.

CONSTITUTION: Cyanophyta Spirillum is dried at 120W130°C for about 3W10sec and formed into a powdery form having a thickness of about 8μm and a length of 300W500μm while the obtained powder is used alone or compounded with a powdery carrier such as activated carbon, zeolite, alumina or a silica gel. The powder alone or the resulting mixture is suspended in a liquid such as water or alcohol along with a proper binder such as a dextrine or starch sige solution while the obtained suspension is spray dried. Or, water or alcohol is reduced to knead the same into a pasty form and the resulting paste is cut and dried while extruded from a nozzle to form a fine chopped strand. By this method, an adsorbent capable of various noxious substances as a tobacco filter, a mask or an air filter is obtained.