To provide a fireproofing member of an inflammable long object penetration part improving fire performance.

The fireproofing member is provided with: plastic half cylindrical members 3 combined in a cylindrical shape; thermal expansible fire resistant material sheets 5 fitted to inner peripheries of the half cylindrical members 3; and metallic half flange members 7 each of which is fitted to one end side in an axial direction of the half cylindrical member 3 and is combined in a flange shape. The half flange member has a screw hole 39 being a fixing part to a fire block object. A projected edge 9 is formed in an outer periphery on one end side in the axial direction of the half cylindrical member 3. A plurality of holding pieces 33 holding the projected edge 9 are formed on an inner peripheral part of the half flange member 7, and the projected edge 9 is held by the holding pieces 33. Thus, the half flange member 7 is attachably/detachably fitted to one end side in the axial direction of the half cylindrical member 3.