A respirator containing filter cases uses cellular elements or positioning boards provided in filter cases to consistently secure a plurality of particle-shape refillable filter materials in place, to prevent air breathing in through the respirator from forming channels between the particle-shape refillable filter materials in the filter cases, so that the particle-shape refillable filter materials in the filter cases can properly filter the incoming air, and the service life of the respirator can be extended; and, using a recessed space formed inside the respirator body, where an appropriate space can be reserved between the casing and the user's nose and mouth to enlarge the breathing area of filtered air passing through the filter cases, reduce pressure drop, and enable less breathing effort to the user even after extended period of time in wearing the present invention of respirator containing filter cases.