To provide a form 1 for an exterior concrete slab on grade, which is used for the formation of the exterior concrete slab on grade, which enables a curved shape with an arbitrary curvature to be easily formed in a neatly finished state, and which is excellent in general-purpose properties.

This form 1 for the exterior concrete slab on grade includes: a plurality of rectangular flexible flat plate-like sheathing boards 2, which dam up the poured concrete; a round pipe 3 which has an upper end provided with a flange 32 fixed to the upper end surface 2c of the sheathing board 2, and which is mounted to the lateral surface 2b on the other side of a concrete placing surface 2a of the sheathing board 2; a reinforcing bar 4 which is inserted through the round pipe 3 and which has a lower end driven into the ground; and connecting implements 5, 6 and 7 for connecting the sheathing boards 2 to one another. The sheathing board 2 is fixed to the ground G by means of the round pipe 3 and the reinforcing bar 4 while being curved depending on the planar shape of the predesigned concrete slab on grade.