Abstract: The primary object of the invention is to provide a sealing material and an injection method that make sure good effects on stopping water and good durability. The inventive sealing material comprises a mixture of Materials A and B, the Material A containing fine-particle silica produced by a process in which a slurry having metallic silicon powders dispersed in water is jetted into a flame for burning and oxidization and having an average particle diameter of 1.0 ?m or less, a dispersant and water and being subjected to wet dispersion, and the Material B containing a calcium compound having an average particle diameter of 1.0 ?m or less, a dispersant and water and being subjected to wet dispersion. The average particle diameter is measured using a leaser diffraction type particle size distribution analyzer without subjecting the silica and the calcium compound to ultrasonic dispersion.