To provide a construction method of a parapet that can shorten a construction period by reducing the number of processes up to the completion of a waterproof backing.

In this construction method of the parapet, a lower end part of an inner template 5 at a parapet form 4 formed built up along the outer periphery of a flat roof 3 is provided with an inclined plate 6 inclined toward the inside of a roof floor face 10 from a rising part 14 of the parapet 1, and then concrete 13 is placed in the parapet form 4.