Abstract: A protective mask of simple structure, to be worn easily at the scene of fires, catches and retains poisonous gas contained in smoke generated by fire. The protective mask comprises a pulp fiber structure (1) having a first fiber layer (2) wherein fibers are layered without twining and mixed with gas absorbent pellets (5), which is placed on a second fiber layer (3) having a skin crust (6) formed by hydrating, pressing and drying the surface of one side of the layer of pulp fibers that are not twined. This pulp fiber structure (1) is wrapped in wrapping material (7) and included in a mask body (8) formed with pleats (9) and provided with an aluminum strip piece (11). The first pulp fiber layer (2) is made by causing pulp fibers, obtained by crashing a pulp sheet (30) in a hammer mill, to temporarily stay in a dead air space (C) within the hammer mill; gas absorbent pellets (5), together with air, are supplied by a jet device to the dead air space (C).