To provide a fire-preventive waterproof filler capable of reliably achieving a prescribed fire-preventive waterproof performance, even when filling postures are changed.

The fire-preventive waterproof filler 1 provided with water impermeability and heat resistance contains, in a coexistent state, components having a water swelling property and components having a thermal expansion property so that the fire-preventive waterproof filler 1 swells entirely both when wetted and heated. Practically, the fire-preventive waterproof filler 1 is prepared by mixing highly water-absorbing resin such as sodium polyacrylate or the like and a water-absorbing inorganic substance (an example of water absorbing and swelling components) with a thermal expansion inorganic substance (an example of thermal expansion components) such as expanded graphite, unburned vermiculite and alkali metal silicate or the like, relative to synthetic rubber (an example of major components) such as an EPDM or the like having the water impermeability and heat resistance, and is configured into a semisolid shape having proper viscosity.