To simplify and ensure installation and fixation to a form while preventing rust formation after installation.

This support for a hollow slab tube is provided with a receiving part 10 having an arcuate part 11, and a mounting part 20 provided on the lower side of nearly the center of the receiving part. The mounting part 20 comprises a support rod 21 with the upper part stuck to the receiving part and with the lower part outer surface formed with a screw 21a; a screw rod 25 concentrically connected to the lower part of the support rod through a connecting member 23; and a nut 27 screwed from the lower end of the screw rod 25. The connecting member 23 is formed in a cylindrical shape with a body made of a non-rusting material such as synthetic resin, with a bottom 23a to abutting on the upper face of the form and with an internal screw 24 with which the screw 21a of the support rod and an upper part 25a of the screw rod are screwed, respectively. The screw rod 25 is formed as a rod body insertable through a through hole formed in the form from above, and formed at the lower end with a tool receiving part 25c for rotating the screw rod to detach it from the connecting member.