To solve a problem of a construction period besides being uneconomical due to idle time and a concrete curing period because of requiring at least three times of placing concrete in the conventional construction of a concrete wall.

In this form for an L-type concrete structure and the application method of the form, a front side sheathing board part 2 is disposed on the front side of a vertical plane 4A of a reinforcing mesh plate 4 composed of the vertical plane 4A with a square front face composed of expanded metal, and a horizontal plane 4B connected in a horizontally bent state to the lower side of the vertical plane. A rear side sheathing board part 3 is disposed on the rear side of the vertical plane 4A of the reinforcing mesh plate 4. The lower end of the rear side sheathing board part 3 is provided with a horizontal bed 3B connected to the upper face of the horizontal plane 4B of the reinforcing mesh plate 4.