To accurately finish a contact surface by pulling up a main body of a form from the side surfaces of a side drain cover product.

In order to use a form for a groove cover, a main body 3 of the form is mounted on a form base 2 and concrete is cast from an opening in the upper surface of the body 3. At that moment, an arched portion 5 at the upper part of the body 3, whose periphery is integrally formed, is made so as to precisely form a curved contact surface of a side drain cover product 4. After the product 4 is cured for a predetermined time period, an end of the main body 3 is pulled up by means of a handle and the body 3 is turned through an axis to rapidly separate the body 3 from the side surface of the product 4 to upwardly pull the body 3. The product 4 obtained has a precisely formed curved surface so that noise is not generated. Thus a product of high quality can be obtained. And since the periphery is made integral, the body 3 can be easily used.