To carry out installation work for an interior material on a concrete surface efficiently and in a short period of time concerning structure to install the interior material such as a soundproof mat on the concrete surface and a concrete nail to be used for it.

A concrete nail 1 is driven through an interior material 11 furnished with a cushioning property attached on a concrete surface by using the concrete nail 1 furnished with a collar 5 a margin of which is a cutting blade 6 directed toward a head end side of the nail on a middle part. At this time, as a hole 10 drilled and provided by the cutting blade 6 of the collar of the concrete nail is formed on the surface side of the interior material 11, the interior material 11 is held by putting a cap 3 having a projection 8 fit in this hole 10 on a head part 2 of the concrete nail 1. When the concrete nail 1 is driven, a soundproof mat in the circumference is never dragged to make a bell-like dent, and it is possible to provide an interior surface a front surface of which is flat and clean.